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[RFC] Integrate commit-graph into 'fsck' and 'gc' #6

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The commit-graph feature is not useful to end users until the commit-graph file is maintained automatically by Git during normal upkeep operations. One natural place to trigger this write is during 'git gc'.

Before automatically generating a commit-graph, we need to be able to verify the contents of a commit-graph file. Integrate commit-graph checks into 'fsck' that check the commit-graph contents against commits in the object database.

Things to think about:

  • Are these the right integration points?
  • gc.commitGraph defaults to true right now for the purpose of testing, but may not be required to start. The goal is to have this default to true eventually, but we may want to delay that until the feature is stable.
  • I implement a "--reachable" option to 'git commit-graph write' that iterates over all refs. This does the same as "git show-ref -s | git commit-graph write --stdin-commits" but I don't know how to pipe two child processes together inside of Git. Perhaps this is a better solution, anyway.

@derrickstolee derrickstolee force-pushed the fsck/upstream branch 5 times, most recently from f44b13c to 65bba1f Compare May 14, 2018 12:19
gitster and others added 25 commits May 23, 2018 14:38
Doc formatting fix.

* nd/doc-header:
  doc: keep first level section header in upper case
The split-index feature had a long-standing and dormant bug in
certain use of the in-core merge machinery, which has been fixed.

* en/unpack-trees-split-index-fix:
  unpack_trees: fix breakage when o->src_index != o->dst_index
Code simplification.

* bp/test-drop-caches:
  test-drop-caches: simplify delay loading of NtSetSystemInformation
Misc doc fixes.

* ah/misc-doc-updates:
  doc: normalize [--options] to [options] in git-diff
  doc: add note about shell quoting to revision.txt
  git-svn: remove ''--add-author-from' for 'commit-diff'
  doc: add '-d' and '-o' for 'git push'
  doc: clarify ignore rules for git ls-files
  doc: align 'diff --no-index' in text and synopsis
  doc: improve formatting in githooks.txt
Performance test updates.

* cc/perf-bisect:
  perf/bisect_run_script: disable codespeed
"git status" learned to pay attention to UI related diff
configuration variables such as diff.renames.

* em/status-rename-config:
  wt-status: use settings from git_diff_ui_config
Typofix.

* nd/completion-aliasfiletype-typofix:
  completion: fix misspelled config key aliasesfiletype
Doc update.

* nd/pack-unreachable-objects-doc:
  pack-objects: validation and documentation about unreachable options
Asciidoctor gives a reasonable imitation for AsciiDoc, but does not
render illustration in a literal block correctly when indented with
HT by default. The problem is fixed by forcing 8-space tabs.

* bc/asciidoctor-tab-width:
  Documentation: render revisions correctly under Asciidoctor
  Documentation: use 8-space tabs with Asciidoctor
The command line completion mechanism (in contrib/) learned to load
custom completion file for "git $command" where $command is a
custom "git-$command" that the end user has on the $PATH when using
newer version of bash.

* fg/completion-external:
  completion: load completion file for external subcommand
Signed-off-by: Junio C Hamano <[email protected]>
Many tests are very focused on the file system representation of the
loose and packed refs code. As there are plans to implement other
ref storage systems, let's migrate these tests to a form that test
the intent of the refs storage system instead of it internals.

This will make clear to readers that these tests do not depend on
which ref backend is used.

The internals of the loose refs backend are still tested in
t1400-update-ref.sh, whereas the tests changed in this patch focus
on testing other aspects.

This patch just takes care of many low hanging fruits. It does not
try to completely solves the issue.

Helped-by: Stefan Beller <[email protected]>
Helped-by: Johannes Schindelin <[email protected]>
Signed-off-by: David Turner <[email protected]>
Signed-off-by: Christian Couder <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
Importing gcc tarballs[1] with import-tars script (in contrib) fails
when hitting a pax extended header.

Make sure we always read the extended attributes from the pax entries,
and store the 'path' value if found to be used in the next ustar entry.

The code to parse pax extended headers was written consulting the Pax
Pax Interchange Format documentation [2].

[1] http://ftp.gnu.org/gnu/gcc/gcc-7.3.0/gcc-7.3.0.tar.xz
[2] https://www.freebsd.org/cgi/man.cgi?manpath=FreeBSD+8-current&query=tar&sektion=5

Signed-off-by: Pedro Alvarez <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
This can be used to "unshelve" a shelved P4 commit into
a git commit.

For example:

  $ git p4 unshelve 12345

The resulting commit ends up in the branch:
   refs/remotes/p4/unshelved/12345

If that branch already exists, it is renamed - for example
the above branch would be saved as p4/unshelved/12345.1.

git-p4 checks that the shelved changelist is based on files
which are at the same Perforce revision as the origin branch
being used for the unshelve (HEAD by default). If they are not,
it will refuse to unshelve. This is to ensure that the unshelved
change does not contain other changes mixed-in.

The reference branch can be changed manually with the "--origin"
option.

The change adds a new Unshelve command class. This just runs the
existing P4Sync code tweaked to handle a shelved changelist.

Signed-off-by: Luke Diamand <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
The only thing these commands need is extra parseopt flag which can be
passed in by OPT_SET_INT_F() and it is a bit more compact than full
struct initialization.

Signed-off-by: Nguyễn Thái Ngọc Duy <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
Commits 2122f8b ("rev-parse: Add support for the ^! and ^@ syntax",
2008-07-26) and 3dd4e73 ("Teach rev-parse the ... syntax.", 2006-07-04)
taught rev-parse new syntax, and used lookup_commit_reference() as part of
their logic.  Neither usage checked the returned commit to see if it was
non-NULL before using it.  Check for NULL and ensure an appropriate error
is reported to the user.

Reported by Florian Weimer and Todd Zullinger.

Helped-by: Jeff King <[email protected]>
Signed-off-by: Elijah Newren <[email protected]>
Reviewed-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
If "git pull --recurse-submodules --rebase" is invoked when the current
branch and its corresponding remote-tracking branch have no merge base,
a "bad object" fatal error occurs. This issue was introduced with commit
a6d7eb2 ("pull: optionally rebase submodules (remote submodule
changes only)", 2017-06-23), which also introduced this feature.

This is because cmd_pull() in builtin/pull.c thus invokes
submodule_touches_in_range() with a null OID as the first parameter.
Ensure that this case works, and document what happens in this case.

Signed-off-by: Jonathan Tan <[email protected]>
Reviewed-by: Stefan Beller <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
The standard for command documentation synopses appears to be:

  [...] means optional
  <...> means replaceable
  [<...>] means both optional and replaceable

So fix a number of doc pages that use incorrect variations of the
above.

Signed-off-by: Robert P. J. Day <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
These tests used pretty strong measures to get a clean slate:
        git rm -rf . &&
        git clean -fdqx &&
        rm -rf .git &&
        git init &&
It's easier, safer (what if a previous test has a bug and accidentally
changes into a directory outside the test path?), and allows re-inspecting
test setup later if we instead just use test_create_repo to put different
tests into separate sub-repositories.

Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
Manually cleaning up from former tests in subsequent ones breaks the
ability to select which tests we want to run.  Use test_when_finished to
avoid this problem.

Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
exec argument is a command, not a commit.

Signed-off-by: Orgad Shaneh <[email protected]>
Acked-by: Johannes Schindelin <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
The git-show-index command is built as its own separate
program. There's really no good reason for this, and it
means we waste extra space on disk (and CPU time running the
linker). Let's fold it in to the main binary as a builtin.

The history here is actually a bit amusing. The program
itself is mostly self-contained, and doesn't even use our
normal pack index code. In a503121 (slim down "git
show-index", 2010-01-21), we even stopped using xmalloc() so
that it could avoid libgit.a entirely. But then 040a655
(cleanup: use internal memory allocation wrapper functions
everywhere, 2011-10-06) switched that back to xmalloc, which
later become ALLOC_ARRAY().

Making it a builtin should give us the best of both worlds:
no wasted space and no need to avoid the usual patterns.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jan 17, 2023
When using a padding specifier in the pretty format passed to git-log(1)
we need to calculate the string length in several places. These string
lengths are stored in `int`s though, which means that these can easily
overflow when the input lengths exceeds 2GB. This can ultimately lead to
an out-of-bounds write when these are used in a call to memcpy(3P):

        ==8340==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x7f1ec62f97fe at pc 0x7f2127e5f427 bp 0x7ffd3bd63de0 sp 0x7ffd3bd63588
    WRITE of size 1 at 0x7f1ec62f97fe thread T0
        #0 0x7f2127e5f426 in __interceptor_memcpy /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:827
        #1 0x5628e96aa605 in format_and_pad_commit pretty.c:1762
        #2 0x5628e96aa7f4 in format_commit_item pretty.c:1801
        #3 0x5628e97cdb24 in strbuf_expand strbuf.c:429
        #4 0x5628e96ab060 in repo_format_commit_message pretty.c:1869
        #5 0x5628e96acd0f in pretty_print_commit pretty.c:2161
        #6 0x5628e95a44c8 in show_log log-tree.c:781
        #7 0x5628e95a76ba in log_tree_commit log-tree.c:1117
        #8 0x5628e922bed5 in cmd_log_walk_no_free builtin/log.c:508
        #9 0x5628e922c35b in cmd_log_walk builtin/log.c:549
        #10 0x5628e922f1a2 in cmd_log builtin/log.c:883
        #11 0x5628e9106993 in run_builtin git.c:466
        #12 0x5628e9107397 in handle_builtin git.c:721
        #13 0x5628e9107b07 in run_argv git.c:788
        #14 0x5628e91088a7 in cmd_main git.c:923
        #15 0x5628e939d682 in main common-main.c:57
        #16 0x7f2127c3c28f  (/usr/lib/libc.so.6+0x2328f)
        #17 0x7f2127c3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
        #18 0x5628e91020e4 in _start ../sysdeps/x86_64/start.S:115

    0x7f1ec62f97fe is located 2 bytes to the left of 4831838265-byte region [0x7f1ec62f9800,0x7f1fe62f9839)
    allocated by thread T0 here:
        #0 0x7f2127ebe7ea in __interceptor_realloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:85
        #1 0x5628e98774d4 in xrealloc wrapper.c:136
        #2 0x5628e97cb01c in strbuf_grow strbuf.c:99
        #3 0x5628e97ccd42 in strbuf_addchars strbuf.c:327
        #4 0x5628e96aa55c in format_and_pad_commit pretty.c:1761
        #5 0x5628e96aa7f4 in format_commit_item pretty.c:1801
        #6 0x5628e97cdb24 in strbuf_expand strbuf.c:429
        #7 0x5628e96ab060 in repo_format_commit_message pretty.c:1869
        #8 0x5628e96acd0f in pretty_print_commit pretty.c:2161
        #9 0x5628e95a44c8 in show_log log-tree.c:781
        #10 0x5628e95a76ba in log_tree_commit log-tree.c:1117
        #11 0x5628e922bed5 in cmd_log_walk_no_free builtin/log.c:508
        #12 0x5628e922c35b in cmd_log_walk builtin/log.c:549
        #13 0x5628e922f1a2 in cmd_log builtin/log.c:883
        #14 0x5628e9106993 in run_builtin git.c:466
        #15 0x5628e9107397 in handle_builtin git.c:721
        #16 0x5628e9107b07 in run_argv git.c:788
        #17 0x5628e91088a7 in cmd_main git.c:923
        #18 0x5628e939d682 in main common-main.c:57
        #19 0x7f2127c3c28f  (/usr/lib/libc.so.6+0x2328f)
        #20 0x7f2127c3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
        #21 0x5628e91020e4 in _start ../sysdeps/x86_64/start.S:115

    SUMMARY: AddressSanitizer: heap-buffer-overflow /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:827 in __interceptor_memcpy
    Shadow bytes around the buggy address:
      0x0fe458c572a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0fe458c572b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0fe458c572c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0fe458c572d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0fe458c572e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
    =>0x0fe458c572f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa[fa]
      0x0fe458c57300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0fe458c57310: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0fe458c57320: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0fe458c57330: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
      0x0fe458c57340: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    Shadow byte legend (one shadow byte represents 8 application bytes):
      Addressable:           00
      Partially addressable: 01 02 03 04 05 06 07
      Heap left redzone:       fa
      Freed heap region:       fd
      Stack left redzone:      f1
      Stack mid redzone:       f2
      Stack right redzone:     f3
      Stack after return:      f5
      Stack use after scope:   f8
      Global redzone:          f9
      Global init order:       f6
      Poisoned by user:        f7
      Container overflow:      fc
      Array cookie:            ac
      Intra object redzone:    bb
      ASan internal:           fe
      Left alloca redzone:     ca
      Right alloca redzone:    cb
    ==8340==ABORTING

The pretty format can also be used in `git archive` operations via the
`export-subst` attribute. So this is what in our opinion makes this a
critical issue in the context of Git forges which allow to download an
archive of user supplied Git repositories.

Fix this vulnerability by using `size_t` instead of `int` to track the
string lengths. Add tests which detect this vulnerability when Git is
compiled with the address sanitizer.

Reported-by: Joern Schneeweisz <[email protected]>
Original-patch-by: Joern Schneeweisz <[email protected]>
Modified-by: Taylor  Blau <[email protected]>
Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jan 17, 2023
With the `%>>(<N>)` pretty formatter, you can ask git-log(1) et al to
steal spaces. To do so we need to look ahead of the next token to see
whether there are spaces there. This loop takes into account ANSI
sequences that end with an `m`, and if it finds any it will skip them
until it finds the first space. While doing so it does not take into
account the buffer's limits though and easily does an out-of-bounds
read.

Add a test that hits this behaviour. While we don't have an easy way to
verify this, the test causes the following failure when run with
`SANITIZE=address`:

    ==37941==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000000baf at pc 0x55ba6f88e0d0 bp 0x7ffc84c50d20 sp 0x7ffc84c50d10
    READ of size 1 at 0x603000000baf thread T0
        #0 0x55ba6f88e0cf in format_and_pad_commit pretty.c:1712
        #1 0x55ba6f88e7b4 in format_commit_item pretty.c:1801
        #2 0x55ba6f9b1ae4 in strbuf_expand strbuf.c:429
        #3 0x55ba6f88f020 in repo_format_commit_message pretty.c:1869
        #4 0x55ba6f890ccf in pretty_print_commit pretty.c:2161
        #5 0x55ba6f7884c8 in show_log log-tree.c:781
        #6 0x55ba6f78b6ba in log_tree_commit log-tree.c:1117
        #7 0x55ba6f40fed5 in cmd_log_walk_no_free builtin/log.c:508
        #8 0x55ba6f41035b in cmd_log_walk builtin/log.c:549
        #9 0x55ba6f4131a2 in cmd_log builtin/log.c:883
        #10 0x55ba6f2ea993 in run_builtin git.c:466
        #11 0x55ba6f2eb397 in handle_builtin git.c:721
        #12 0x55ba6f2ebb07 in run_argv git.c:788
        #13 0x55ba6f2ec8a7 in cmd_main git.c:923
        #14 0x55ba6f581682 in main common-main.c:57
        #15 0x7f2d08c3c28f  (/usr/lib/libc.so.6+0x2328f)
        #16 0x7f2d08c3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
        #17 0x55ba6f2e60e4 in _start ../sysdeps/x86_64/start.S:115

    0x603000000baf is located 1 bytes to the left of 24-byte region [0x603000000bb0,0x603000000bc8)
    allocated by thread T0 here:
        #0 0x7f2d08ebe7ea in __interceptor_realloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:85
        #1 0x55ba6fa5b494 in xrealloc wrapper.c:136
        #2 0x55ba6f9aefdc in strbuf_grow strbuf.c:99
        #3 0x55ba6f9b0a06 in strbuf_add strbuf.c:298
        #4 0x55ba6f9b1a25 in strbuf_expand strbuf.c:418
        #5 0x55ba6f88f020 in repo_format_commit_message pretty.c:1869
        #6 0x55ba6f890ccf in pretty_print_commit pretty.c:2161
        #7 0x55ba6f7884c8 in show_log log-tree.c:781
        #8 0x55ba6f78b6ba in log_tree_commit log-tree.c:1117
        #9 0x55ba6f40fed5 in cmd_log_walk_no_free builtin/log.c:508
        #10 0x55ba6f41035b in cmd_log_walk builtin/log.c:549
        #11 0x55ba6f4131a2 in cmd_log builtin/log.c:883
        #12 0x55ba6f2ea993 in run_builtin git.c:466
        #13 0x55ba6f2eb397 in handle_builtin git.c:721
        #14 0x55ba6f2ebb07 in run_argv git.c:788
        #15 0x55ba6f2ec8a7 in cmd_main git.c:923
        #16 0x55ba6f581682 in main common-main.c:57
        #17 0x7f2d08c3c28f  (/usr/lib/libc.so.6+0x2328f)
        #18 0x7f2d08c3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
        #19 0x55ba6f2e60e4 in _start ../sysdeps/x86_64/start.S:115

    SUMMARY: AddressSanitizer: heap-buffer-overflow pretty.c:1712 in format_and_pad_commit
    Shadow bytes around the buggy address:
      0x0c067fff8120: fa fa fd fd fd fa fa fa fd fd fd fa fa fa fd fd
      0x0c067fff8130: fd fd fa fa fd fd fd fd fa fa fd fd fd fa fa fa
      0x0c067fff8140: fd fd fd fa fa fa fd fd fd fa fa fa fd fd fd fa
      0x0c067fff8150: fa fa fd fd fd fd fa fa 00 00 00 fa fa fa fd fd
      0x0c067fff8160: fd fa fa fa fd fd fd fa fa fa fd fd fd fa fa fa
    =>0x0c067fff8170: fd fd fd fa fa[fa]00 00 00 fa fa fa 00 00 00 fa
      0x0c067fff8180: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c067fff8190: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c067fff81a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c067fff81b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c067fff81c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
    Shadow byte legend (one shadow byte represents 8 application bytes):
      Addressable:           00
      Partially addressable: 01 02 03 04 05 06 07
      Heap left redzone:       fa
      Freed heap region:       fd
      Stack left redzone:      f1
      Stack mid redzone:       f2
      Stack right redzone:     f3
      Stack after return:      f5
      Stack use after scope:   f8
      Global redzone:          f9
      Global init order:       f6
      Poisoned by user:        f7
      Container overflow:      fc
      Array cookie:            ac
      Intra object redzone:    bb
      ASan internal:           fe
      Left alloca redzone:     ca
      Right alloca redzone:    cb

Luckily enough, this would only cause us to copy the out-of-bounds data
into the formatted commit in case we really had an ANSI sequence
preceding our buffer. So this bug likely has no security consequences.

Fix it regardless by not traversing past the buffer's start.

Reported-by: Patrick Steinhardt <[email protected]>
Reported-by: Eric Sesterhenn <[email protected]>
Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jan 17, 2023
An out-of-bounds read can be triggered when parsing an incomplete
padding format string passed via `--pretty=format` or in Git archives
when files are marked with the `export-subst` gitattribute.

This bug exists since we have introduced support for truncating output
via the `trunc` keyword a7f01c6 (pretty: support truncating in %>, %<
and %><, 2013-04-19). Before this commit, we used to find the end of the
formatting string by using strchr(3P). This function returns a `NULL`
pointer in case the character in question wasn't found. The subsequent
check whether any character was found thus simply checked the returned
pointer. After the commit we switched to strcspn(3P) though, which only
returns the offset to the first found character or to the trailing NUL
byte. As the end pointer is now computed by adding the offset to the
start pointer it won't be `NULL` anymore, and as a consequence the check
doesn't do anything anymore.

The out-of-bounds data that is being read can in fact end up in the
formatted string. As a consequence, it is possible to leak memory
contents either by calling git-log(1) or via git-archive(1) when any of
the archived files is marked with the `export-subst` gitattribute.

    ==10888==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000000398 at pc 0x7f0356047cb2 bp 0x7fff3ffb95d0 sp 0x7fff3ffb8d78
    READ of size 1 at 0x602000000398 thread T0
        #0 0x7f0356047cb1 in __interceptor_strchrnul /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:725
        #1 0x563b7cec9a43 in strbuf_expand strbuf.c:417
        #2 0x563b7cda7060 in repo_format_commit_message pretty.c:1869
        #3 0x563b7cda8d0f in pretty_print_commit pretty.c:2161
        #4 0x563b7cca04c8 in show_log log-tree.c:781
        #5 0x563b7cca36ba in log_tree_commit log-tree.c:1117
        #6 0x563b7c927ed5 in cmd_log_walk_no_free builtin/log.c:508
        #7 0x563b7c92835b in cmd_log_walk builtin/log.c:549
        #8 0x563b7c92b1a2 in cmd_log builtin/log.c:883
        #9 0x563b7c802993 in run_builtin git.c:466
        #10 0x563b7c803397 in handle_builtin git.c:721
        #11 0x563b7c803b07 in run_argv git.c:788
        #12 0x563b7c8048a7 in cmd_main git.c:923
        #13 0x563b7ca99682 in main common-main.c:57
        #14 0x7f0355e3c28f  (/usr/lib/libc.so.6+0x2328f)
        #15 0x7f0355e3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
        #16 0x563b7c7fe0e4 in _start ../sysdeps/x86_64/start.S:115

    0x602000000398 is located 0 bytes to the right of 8-byte region [0x602000000390,0x602000000398)
    allocated by thread T0 here:
        #0 0x7f0356072faa in __interceptor_strdup /usr/src/debug/gcc/libsanitizer/asan/asan_interceptors.cpp:439
        #1 0x563b7cf7317c in xstrdup wrapper.c:39
        #2 0x563b7cd9a06a in save_user_format pretty.c:40
        #3 0x563b7cd9b3e5 in get_commit_format pretty.c:173
        #4 0x563b7ce54ea0 in handle_revision_opt revision.c:2456
        #5 0x563b7ce597c9 in setup_revisions revision.c:2850
        #6 0x563b7c9269e0 in cmd_log_init_finish builtin/log.c:269
        #7 0x563b7c927362 in cmd_log_init builtin/log.c:348
        #8 0x563b7c92b193 in cmd_log builtin/log.c:882
        #9 0x563b7c802993 in run_builtin git.c:466
        #10 0x563b7c803397 in handle_builtin git.c:721
        #11 0x563b7c803b07 in run_argv git.c:788
        #12 0x563b7c8048a7 in cmd_main git.c:923
        #13 0x563b7ca99682 in main common-main.c:57
        #14 0x7f0355e3c28f  (/usr/lib/libc.so.6+0x2328f)
        #15 0x7f0355e3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
        #16 0x563b7c7fe0e4 in _start ../sysdeps/x86_64/start.S:115

    SUMMARY: AddressSanitizer: heap-buffer-overflow /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:725 in __interceptor_strchrnul
    Shadow bytes around the buggy address:
      0x0c047fff8020: fa fa fd fd fa fa 00 06 fa fa 05 fa fa fa fd fd
      0x0c047fff8030: fa fa 00 02 fa fa 06 fa fa fa 05 fa fa fa fd fd
      0x0c047fff8040: fa fa 00 07 fa fa 03 fa fa fa fd fd fa fa 00 00
      0x0c047fff8050: fa fa 00 01 fa fa fd fd fa fa 00 00 fa fa 00 01
      0x0c047fff8060: fa fa 00 06 fa fa 00 06 fa fa 05 fa fa fa 05 fa
    =>0x0c047fff8070: fa fa 00[fa]fa fa fd fa fa fa fd fd fa fa fd fd
      0x0c047fff8080: fa fa fd fd fa fa 00 00 fa fa 00 fa fa fa fd fa
      0x0c047fff8090: fa fa fd fd fa fa 00 00 fa fa fa fa fa fa fa fa
      0x0c047fff80a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c047fff80b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c047fff80c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
    Shadow byte legend (one shadow byte represents 8 application bytes):
      Addressable:           00
      Partially addressable: 01 02 03 04 05 06 07
      Heap left redzone:       fa
      Freed heap region:       fd
      Stack left redzone:      f1
      Stack mid redzone:       f2
      Stack right redzone:     f3
      Stack after return:      f5
      Stack use after scope:   f8
      Global redzone:          f9
      Global init order:       f6
      Poisoned by user:        f7
      Container overflow:      fc
      Array cookie:            ac
      Intra object redzone:    bb
      ASan internal:           fe
      Left alloca redzone:     ca
      Right alloca redzone:    cb
    ==10888==ABORTING

Fix this bug by checking whether `end` points at the trailing NUL byte.
Add a test which catches this out-of-bounds read and which demonstrates
that we used to write out-of-bounds data into the formatted message.

Reported-by: Markus Vervier <[email protected]>
Original-patch-by: Markus Vervier <[email protected]>
Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jan 17, 2023
The return type of both `utf8_strwidth()` and `utf8_strnwidth()` is
`int`, but we operate on string lengths which are typically of type
`size_t`. This means that when the string is longer than `INT_MAX`, we
will overflow and thus return a negative result.

This can lead to an out-of-bounds write with `--pretty=format:%<1)%B`
and a commit message that is 2^31+1 bytes long:

    =================================================================
    ==26009==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x603000001168 at pc 0x7f95c4e5f427 bp 0x7ffd8541c900 sp 0x7ffd8541c0a8
    WRITE of size 2147483649 at 0x603000001168 thread T0
        #0 0x7f95c4e5f426 in __interceptor_memcpy /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:827
        #1 0x5612bbb1068c in format_and_pad_commit pretty.c:1763
        #2 0x5612bbb1087a in format_commit_item pretty.c:1801
        #3 0x5612bbc33bab in strbuf_expand strbuf.c:429
        #4 0x5612bbb110e7 in repo_format_commit_message pretty.c:1869
        #5 0x5612bbb12d96 in pretty_print_commit pretty.c:2161
        #6 0x5612bba0a4d5 in show_log log-tree.c:781
        #7 0x5612bba0d6c7 in log_tree_commit log-tree.c:1117
        #8 0x5612bb691ed5 in cmd_log_walk_no_free builtin/log.c:508
        #9 0x5612bb69235b in cmd_log_walk builtin/log.c:549
        #10 0x5612bb6951a2 in cmd_log builtin/log.c:883
        #11 0x5612bb56c993 in run_builtin git.c:466
        #12 0x5612bb56d397 in handle_builtin git.c:721
        #13 0x5612bb56db07 in run_argv git.c:788
        #14 0x5612bb56e8a7 in cmd_main git.c:923
        #15 0x5612bb803682 in main common-main.c:57
        #16 0x7f95c4c3c28f  (/usr/lib/libc.so.6+0x2328f)
        #17 0x7f95c4c3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
        #18 0x5612bb5680e4 in _start ../sysdeps/x86_64/start.S:115

    0x603000001168 is located 0 bytes to the right of 24-byte region [0x603000001150,0x603000001168)
    allocated by thread T0 here:
        #0 0x7f95c4ebe7ea in __interceptor_realloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:85
        #1 0x5612bbcdd556 in xrealloc wrapper.c:136
        #2 0x5612bbc310a3 in strbuf_grow strbuf.c:99
        #3 0x5612bbc32acd in strbuf_add strbuf.c:298
        #4 0x5612bbc33aec in strbuf_expand strbuf.c:418
        #5 0x5612bbb110e7 in repo_format_commit_message pretty.c:1869
        #6 0x5612bbb12d96 in pretty_print_commit pretty.c:2161
        #7 0x5612bba0a4d5 in show_log log-tree.c:781
        #8 0x5612bba0d6c7 in log_tree_commit log-tree.c:1117
        #9 0x5612bb691ed5 in cmd_log_walk_no_free builtin/log.c:508
        #10 0x5612bb69235b in cmd_log_walk builtin/log.c:549
        #11 0x5612bb6951a2 in cmd_log builtin/log.c:883
        #12 0x5612bb56c993 in run_builtin git.c:466
        #13 0x5612bb56d397 in handle_builtin git.c:721
        #14 0x5612bb56db07 in run_argv git.c:788
        #15 0x5612bb56e8a7 in cmd_main git.c:923
        #16 0x5612bb803682 in main common-main.c:57
        #17 0x7f95c4c3c28f  (/usr/lib/libc.so.6+0x2328f)

    SUMMARY: AddressSanitizer: heap-buffer-overflow /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:827 in __interceptor_memcpy
    Shadow bytes around the buggy address:
      0x0c067fff81d0: fd fd fd fa fa fa fd fd fd fa fa fa fd fd fd fa
      0x0c067fff81e0: fa fa fd fd fd fd fa fa fd fd fd fd fa fa fd fd
      0x0c067fff81f0: fd fa fa fa fd fd fd fa fa fa fd fd fd fa fa fa
      0x0c067fff8200: fd fd fd fa fa fa fd fd fd fd fa fa 00 00 00 fa
      0x0c067fff8210: fa fa fd fd fd fa fa fa fd fd fd fa fa fa fd fd
    =>0x0c067fff8220: fd fa fa fa fd fd fd fa fa fa 00 00 00[fa]fa fa
      0x0c067fff8230: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c067fff8240: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c067fff8250: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c067fff8260: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
      0x0c067fff8270: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
    Shadow byte legend (one shadow byte represents 8 application bytes):
      Addressable:           00
      Partially addressable: 01 02 03 04 05 06 07
      Heap left redzone:       fa
      Freed heap region:       fd
      Stack left redzone:      f1
      Stack mid redzone:       f2
      Stack right redzone:     f3
      Stack after return:      f5
      Stack use after scope:   f8
      Global redzone:          f9
      Global init order:       f6
      Poisoned by user:        f7
      Container overflow:      fc
      Array cookie:            ac
      Intra object redzone:    bb
      ASan internal:           fe
      Left alloca redzone:     ca
      Right alloca redzone:    cb
    ==26009==ABORTING

Now the proper fix for this would be to convert both functions to return
an `size_t` instead of an `int`. But given that this commit may be part
of a security release, let's instead do the minimal viable fix and die
in case we see an overflow.

Add a test that would have previously caused us to crash.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Mar 15, 2023
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request Mar 15, 2023
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request May 11, 2023
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request Aug 23, 2023
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request Sep 27, 2023
When t5583-push-branches.sh was originally introduced via 425b4d7
(push: introduce '--branches' option, 2023-05-06), it was not leak-free.
In fact, the test did not even run correctly until 022fbb6 (t5583:
fix shebang line, 2023-05-12), but after applying that patch, we see a
failure at t5583.8:

    ==2529087==ERROR: LeakSanitizer: detected memory leaks

    Direct leak of 384 byte(s) in 1 object(s) allocated from:
        #0 0x7fb536330986 in __interceptor_realloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:98
        #1 0x55e07606cbf9 in xrealloc wrapper.c:140
        #2 0x55e075fb6cb3 in prio_queue_put prio-queue.c:42
        #3 0x55e075ec81cb in get_reachable_subset commit-reach.c:917
        #4 0x55e075fe9cce in add_missing_tags remote.c:1518
        #5 0x55e075fea1e4 in match_push_refs remote.c:1665
        #6 0x55e076050a8e in transport_push transport.c:1378
        #7 0x55e075e2eb74 in push_with_options builtin/push.c:401
        #8 0x55e075e2edb0 in do_push builtin/push.c:458
        #9 0x55e075e2ff7a in cmd_push builtin/push.c:702
        #10 0x55e075d8aaf0 in run_builtin git.c:452
        #11 0x55e075d8af08 in handle_builtin git.c:706
        #12 0x55e075d8b12c in run_argv git.c:770
        #13 0x55e075d8b6a0 in cmd_main git.c:905
        #14 0x55e075e81f07 in main common-main.c:60
        #15 0x7fb5360ab6c9 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
        #16 0x7fb5360ab784 in __libc_start_main_impl ../csu/libc-start.c:360
        #17 0x55e075d88f40 in _start (git+0x1ff40) (BuildId: 38ad998b85a535e786129979443630d025ec2453)

    SUMMARY: LeakSanitizer: 384 byte(s) leaked in 1 allocation(s).

This leak was addressed independently via 68b5117 (commit-reach: fix
memory leak in get_reachable_subset(), 2023-06-03), which makes t5583
leak-free.

But t5583 was not in the tree when 68b5117 was written, and the two
only met after the latter was merged back in via 693bde4 (Merge
branch 'mh/commit-reach-get-reachable-plug-leak', 2023-06-20).

At that point, t5583 was leak-free. Let's mark it as such accordingly.

Signed-off-by: Taylor Blau <[email protected]>
Acked-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Apr 4, 2024
The t5309 script triggers a racy false positive with SANITIZE=leak on a
multi-core system. Running with "--stress --run=6" usually fails within
10 seconds or so for me, complaining with something like:

    + git index-pack --fix-thin --stdin
    fatal: REF_DELTA at offset 46 already resolved (duplicate base 01d7713666f4de822776c7622c10f1b07de280dc?)

    =================================================================
    ==3904583==ERROR: LeakSanitizer: detected memory leaks

    Direct leak of 32 byte(s) in 1 object(s) allocated from:
        #0 0x7fa790d01986 in __interceptor_realloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:98
        #1 0x7fa790add769 in __pthread_getattr_np nptl/pthread_getattr_np.c:180
        #2 0x7fa790d117c5 in __sanitizer::GetThreadStackTopAndBottom(bool, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:150
        #3 0x7fa790d11957 in __sanitizer::GetThreadStackAndTls(bool, unsigned long*, unsigned long*, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:598
        #4 0x7fa790d03fe8 in __lsan::ThreadStart(unsigned int, unsigned long long, __sanitizer::ThreadType) ../../../../src/libsanitizer/lsan/lsan_posix.cpp:51
        #5 0x7fa790d013fd in __lsan_thread_start_func ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:440
        #6 0x7fa790adc3eb in start_thread nptl/pthread_create.c:444
        #7 0x7fa790b5ca5b in clone3 ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

    SUMMARY: LeakSanitizer: 32 byte(s) leaked in 1 allocation(s).
    Aborted

What happens is this:

  0. We construct a bogus pack with a duplicate object in it and trigger
     index-pack.

  1. We spawn a bunch of worker threads to resolve deltas (on my system
     it is 16 threads).

  2. One of the threads sees the duplicate object and bails by calling
     exit(), taking down all of the threads. This is expected and is the
     point of the test.

  3. At the time exit() is called, we may still be spawning threads from
     the main process via pthread_create(). LSan hooks thread creation
     to update its book-keeping; it has to know where each thread's
     stack is (so it can find entry points for reachable memory). So it
     calls pthread_getattr_np() to get information about the new thread.
     That may allocate memory that must be freed with a matching call to
     pthread_attr_destroy(). Probably LSan does that immediately, but
     if you're unlucky enough, the exit() will happen while it's between
     those two calls, and the allocated pthread_attr_t appears as a
     leak.

This isn't a real leak. It's not even in our code, but rather in the
LSan instrumentation code. So we could just ignore it. But the false
positive can cause people to waste time tracking it down.

It's possibly something that LSan could protect against (e.g., cover the
getattr/destroy pair with a mutex, and then in the final post-exit()
check for leaks try to take the same mutex). But I don't know enough
about LSan to say if that's a reasonable approach or not (or if my
analysis is even completely correct).

In the meantime, it's pretty easy to avoid the race by making creation
of the worker threads "atomic". That is, we'll spawn all of them before
letting any of them start to work. That's easy to do because we already
have a work_lock() mutex for handing out that work. If the main process
takes it, then all of the threads will immediately block until we've
finished spawning and released it.

This shouldn't make any practical difference for non-LSan runs. The
thread spawning is quick, and could happen before any worker thread gets
scheduled anyway.

Probably other spots that use threads are subject to the same issues.
But since we have to manually insert locking (and since this really is
kind of a hack), let's not bother with them unless somebody experiences
a similar racy false-positive in practice.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Apr 30, 2024
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request May 31, 2024
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jun 19, 2024
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jul 3, 2024
When performing multi-pack reuse, reuse_partial_packfile_from_bitmap()
is responsible for generating an array of bitmapped_pack structs from
which to perform reuse.

In the multi-pack case, we loop over the MIDXs packs and copy the result
of calling `nth_bitmapped_pack()` to construct the list of reusable
paths.

But we may also want to do pack-reuse over a single pack, either because
we only had one pack to perform reuse over (in the case of single-pack
bitmaps), or because we explicitly asked to do single pack reuse even
with a MIDX[^1].

When this is the case, the array we generate of reusable packs contains
only a single element, which is either (a) the pack attached to the
single-pack bitmap, or (b) the MIDX's preferred pack.

In 795006f (pack-bitmap: gracefully handle missing BTMP chunks,
2024-04-15), we refactored the reuse_partial_packfile_from_bitmap()
function and stopped assigning the pack_int_id field when reusing only
the MIDX's preferred pack. This results in an uninitialized read down in
try_partial_reuse() like so:

    ==7474==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x55c5cd191dde in try_partial_reuse pack-bitmap.c:1887:8
    #1 0x55c5cd191dde in reuse_partial_packfile_from_bitmap_1 pack-bitmap.c:2001:8
    #2 0x55c5cd191dde in reuse_partial_packfile_from_bitmap pack-bitmap.c:2105:3
    #3 0x55c5cce0bd0e in get_object_list_from_bitmap builtin/pack-objects.c:4043:3
    #4 0x55c5cce0bd0e in get_object_list builtin/pack-objects.c:4156:27
    #5 0x55c5cce0bd0e in cmd_pack_objects builtin/pack-objects.c:4596:3
    #6 0x55c5ccc8fac8 in run_builtin git.c:474:11

which happens when try_partial_reuse() tries to call
midx_pair_to_pack_pos() when it tries to reject cross-pack deltas.

Avoid the uninitialized read by ensuring that the pack_int_id field is
set in the single-pack reuse case by setting it to either the MIDX
preferred pack's pack_int_id, or '-1', in the case of single-pack
bitmaps.  In the latter case, we never read the pack_int_id field, so
the choice of '-1' is intentional as a "garbage in, garbage out"
measure.

Guard against further regressions in this area by adding a test which
ensures that we do not throw out deltas from the preferred pack as
"cross-pack" due to an uninitialized pack_int_id.

[^1]: This can happen for a couple of reasons, either because the
  repository is configured with 'pack.allowPackReuse=(true|single)', or
  because the MIDX was generated prior to the introduction of the BTMP
  chunk, which contains information necessary to perform multi-pack
  reuse.

Reported-by: Kyle Lippincott <[email protected]>
Signed-off-by: Taylor Blau <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jul 3, 2024
Memory sanitizer (msan) is detecting a use of an uninitialized variable
(`size`) in `read_attr_from_index`:

    ==2268==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x5651f3416504 in read_attr_from_index git/attr.c:868:11
    #1 0x5651f3415530 in read_attr git/attr.c
    #2 0x5651f3413d74 in bootstrap_attr_stack git/attr.c:968:6
    #3 0x5651f3413d74 in prepare_attr_stack git/attr.c:1004:2
    #4 0x5651f3413d74 in collect_some_attrs git/attr.c:1199:2
    #5 0x5651f3413144 in git_check_attr git/attr.c:1345:2
    #6 0x5651f34728da in convert_attrs git/convert.c:1320:2
    #7 0x5651f3473425 in would_convert_to_git_filter_fd git/convert.c:1373:2
    #8 0x5651f357a35e in index_fd git/object-file.c:2630:34
    #9 0x5651f357aa15 in index_path git/object-file.c:2657:7
    #10 0x5651f35db9d9 in add_to_index git/read-cache.c:766:7
    #11 0x5651f35dc170 in add_file_to_index git/read-cache.c:799:9
    #12 0x5651f321f9b2 in add_files git/builtin/add.c:346:7
    #13 0x5651f321f9b2 in cmd_add git/builtin/add.c:565:18
    #14 0x5651f321d327 in run_builtin git/git.c:474:11
    #15 0x5651f321bc9e in handle_builtin git/git.c:729:3
    #16 0x5651f321a792 in run_argv git/git.c:793:4
    #17 0x5651f321a792 in cmd_main git/git.c:928:19
    #18 0x5651f33dde1f in main git/common-main.c:62:11

The issue exists because `size` is an output parameter from
`read_blob_data_from_index`, but it's only modified if
`read_blob_data_from_index` returns non-NULL. The read of `size` when
calling `read_attr_from_buf` unconditionally may read from an
uninitialized value. `read_attr_from_buf` checks that `buf` is non-NULL
before reading from `size`, but by then it's already too late: the
uninitialized read will have happened already. Furthermore, there's no
guarantee that the compiler won't reorder things so that it checks
`size` before checking `!buf`.

Make the call to `read_attr_from_buf` conditional on `buf` being
non-NULL, ensuring that `size` is not read if it's never set.

Signed-off-by: Kyle Lippincott <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jul 19, 2024
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request Aug 23, 2024
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request Sep 5, 2024
It was recently reported that concurrent reads and writes may cause the
reftable backend to segfault. The root cause of this is that we do not
properly keep track of reftable readers across reloads.

Suppose that you have a reftable iterator and then decide to reload the
stack while iterating through the iterator. When the stack has been
rewritten since we have created the iterator, then we would end up
discarding a subset of readers that may still be in use by the iterator.
The consequence is that we now try to reference deallocated memory,
which of course segfaults.

One way to trigger this is in t5616, where some background maintenance
jobs have been leaking from one test into another. This leads to stack
traces like the following one:

  + git -c protocol.version=0 -C pc1 fetch --filter=blob:limit=29999 --refetch origin
  AddressSanitizer:DEADLYSIGNAL
  =================================================================
  ==657994==ERROR: AddressSanitizer: SEGV on unknown address 0x7fa0f0ec6089 (pc 0x55f23e52ddf9 bp
0x7ffe7bfa1700 sp 0x7ffe7bfa1700 T0)
  ==657994==The signal is caused by a READ memory access.
      #0 0x55f23e52ddf9 in get_var_int reftable/record.c:29
      #1 0x55f23e53295e in reftable_decode_keylen reftable/record.c:170
      #2 0x55f23e532cc0 in reftable_decode_key reftable/record.c:194
      #3 0x55f23e54e72e in block_iter_next reftable/block.c:398
      #4 0x55f23e5573dc in table_iter_next_in_block reftable/reader.c:240
      #5 0x55f23e5573dc in table_iter_next reftable/reader.c:355
      #6 0x55f23e5573dc in table_iter_next reftable/reader.c:339
      #7 0x55f23e551283 in merged_iter_advance_subiter reftable/merged.c:69
      #8 0x55f23e55169e in merged_iter_next_entry reftable/merged.c:123
      #9 0x55f23e55169e in merged_iter_next_void reftable/merged.c:172
      #10 0x55f23e537625 in reftable_iterator_next_ref reftable/generic.c:175
      #11 0x55f23e2cf9c6 in reftable_ref_iterator_advance refs/reftable-backend.c:464
      #12 0x55f23e2d996e in ref_iterator_advance refs/iterator.c:13
      #13 0x55f23e2d996e in do_for_each_ref_iterator refs/iterator.c:452
      #14 0x55f23dca6767 in get_ref_map builtin/fetch.c:623
      #15 0x55f23dca6767 in do_fetch builtin/fetch.c:1659
      #16 0x55f23dca6767 in fetch_one builtin/fetch.c:2133
      #17 0x55f23dca6767 in cmd_fetch builtin/fetch.c:2432
      #18 0x55f23dba7764 in run_builtin git.c:484
      #19 0x55f23dba7764 in handle_builtin git.c:741
      #20 0x55f23dbab61e in run_argv git.c:805
      #21 0x55f23dbab61e in cmd_main git.c:1000
      #22 0x55f23dba4781 in main common-main.c:64
      #23 0x7fa0f063fc89 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
      #24 0x7fa0f063fd44 in __libc_start_main_impl ../csu/libc-start.c:360
      #25 0x55f23dba6ad0 in _start (git+0xadfad0) (BuildId: 803b2b7f59beb03d7849fb8294a8e2145dd4aa27)

While it is somewhat awkward that the maintenance processes survive
tests in the first place, it is totally expected that reftables should
work alright with concurrent writers. Seemingly they don't.

The only underlying resource that we need to care about in this context
is the reftable reader, which is responsible for reading a single table
from disk. These readers get discarded immediately (unless reused) when
calling `reftable_stack_reload()`, which is wrong. We can only close
them once we know that there are no iterators using them anymore.

Prepare for a fix by converting the reftable readers to be refcounted.

Reported-by: Jeff King <[email protected]>
Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Sep 30, 2024
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request Oct 9, 2024
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
derrickstolee pushed a commit that referenced this pull request Oct 9, 2024
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
dscho added a commit that referenced this pull request Dec 10, 2024
Includes these pull requests:

	#1
	#6
	#10
	#11
	git#157
	git#212
	git#260
	git#270

Signed-off-by: Derrick Stolee <[email protected]>
dscho added a commit that referenced this pull request Dec 10, 2024
An internal customer reported a segfault when running `git
sparse-checkout set` with the `index.sparse` config enabled. I was
unable to reproduce it locally, but with their help we debugged into the
failing process and discovered the following stacktrace:

```
#0  0x00007ff6318fb7b0 in rehash (map=0x3dfb00d0440, newsize=1048576) at hashmap.c:125
#1  0x00007ff6318fbc66 in hashmap_add (map=0x3dfb00d0440, entry=0x3dfb5c58bc8) at hashmap.c:247
#2  0x00007ff631937a70 in hash_index_entry (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:122
#3  0x00007ff631938a2f in add_name_hash (istate=0x3dfb00d0400, ce=0x3dfb5c58bc8) at name-hash.c:638
#4  0x00007ff631a064de in set_index_entry (istate=0x3dfb00d0400, nr=8291, ce=0x3dfb5c58bc8) at sparse-index.c:255
#5  0x00007ff631a06692 in add_path_to_index (oid=0x5ff130, base=0x5ff580, path=0x3dfb4b725da "<redacted>", mode=33188, context=0x5ff570)    at sparse-index.c:307
#6  0x00007ff631a3b48c in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41f60, base=0x5ff580, depth=2, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:46
#7  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41e80, base=0x5ff580, depth=1, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#8  0x00007ff631a3b60b in read_tree_at (r=0x7ff631c026a0 <the_repo>, tree=0x3dfb5b41ac8, base=0x5ff580, depth=0, pathspec=0x5ff5a0,    fn=0x7ff631a064e5 <add_path_to_index>, context=0x5ff570) at tree.c:80
#9  0x00007ff631a06a95 in expand_index (istate=0x3dfb00d0100, pl=0x0) at sparse-index.c:422
#10 0x00007ff631a06cbd in ensure_full_index (istate=0x3dfb00d0100) at sparse-index.c:456
#11 0x00007ff631990d08 in index_name_stage_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21, stage=0,    search_mode=EXPAND_SPARSE) at read-cache.c:556
#12 0x00007ff631990d6c in index_name_pos (istate=0x3dfb00d0100, name=0x3dfb0020080 "algorithm/levenshtein", namelen=21) at read-cache.c:566
#13 0x00007ff63180dbb5 in sanitize_paths (argc=185, argv=0x3dfb0030018, prefix=0x0, skip_checks=0) at builtin/sparse-checkout.c:756
#14 0x00007ff63180de50 in sparse_checkout_set (argc=185, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:860
#15 0x00007ff63180e6c5 in cmd_sparse_checkout (argc=186, argv=0x3dfb0030018, prefix=0x0) at builtin/sparse-checkout.c:1063
#16 0x00007ff6317234cb in run_builtin (p=0x7ff631ad9b38 <commands+2808>, argc=187, argv=0x3dfb0030018) at git.c:548
#17 0x00007ff6317239c0 in handle_builtin (argc=187, argv=0x3dfb0030018) at git.c:808
#18 0x00007ff631723c7d in run_argv (argcp=0x5ffdd0, argv=0x5ffd78) at git.c:877
#19 0x00007ff6317241d1 in cmd_main (argc=187, argv=0x3dfb0030018) at git.c:1017
#20 0x00007ff631838b60 in main (argc=190, argv=0x3dfb0030000) at common-main.c:64 
```

The very bottom of the stack being the `rehash()` method from
`hashmap.c` as called within the `name-hash` API made me look at where
these hashmaps were being used in the sparse index logic. These were
being copied across indexes, which seems dangerous. Indeed, clearing
these hashmaps and setting them as not initialized fixes the segfault.

The second commit is a response to a test failure that happens in
`t1092-sparse-checkout-compatibility.sh` where `git stash pop` starts to
fail because the underlying `git checkout-index` process fails due to
colliding files. Passing the `-f` flag appears to work, but it's unclear
why this name-hash change causes that change in behavior.
derrickstolee pushed a commit that referenced this pull request Jan 6, 2025
This one is a little bit more curious. In t6112, we have a test that
exercises the `git rev-list --filter` option with invalid filters. We
execute git-rev-list(1) via `test_must_fail`, which means that we check
for leaks even though Git exits with an error code. This causes the
following leak:

    Direct leak of 27 byte(s) in 1 object(s) allocated from:
        #0 0x5555555e6946 in realloc.part.0 lsan_interceptors.cpp.o
        #1 0x5555558fb4b6 in xrealloc wrapper.c:137:8
        #2 0x5555558b6e06 in strbuf_grow strbuf.c:112:2
        #3 0x5555558b7550 in strbuf_add strbuf.c:311:2
        #4 0x5555557c1a88 in strbuf_addstr strbuf.h:310:2
        #5 0x5555557c1d4c in parse_list_objects_filter list-objects-filter-options.c:261:3
        #6 0x555555885ead in handle_revision_pseudo_opt revision.c:2899:3
        #7 0x555555884e20 in setup_revisions revision.c:3014:11
        #8 0x5555556c4b42 in cmd_rev_list builtin/rev-list.c:588:9
        #9 0x5555555ec5e3 in run_builtin git.c:483:11
        #10 0x5555555eb1e4 in handle_builtin git.c:749:13
        #11 0x5555555ec001 in run_argv git.c:819:4
        #12 0x5555555eaf94 in cmd_main git.c:954:19
        #13 0x5555556fd569 in main common-main.c:64:11
        #14 0x7ffff7ca714d in __libc_start_call_main (.../lib/libc.so.6+0x2a14d)
        #15 0x7ffff7ca7208 in __libc_start_main@GLIBC_2.2.5 (.../libc.so.6+0x2a208)
        #16 0x5555555ad064 in _start (git+0x59064)

This leak is valid, as we call `die()` and do not clean up the memory at
all. But what's curious is that this is the only leak reported, because
we don't clean up any other allocated memory, either, and I have no idea
why the leak sanitizer treats this buffer specially.

In any case, we can work around the leak by shuffling things around a
bit. Instead of calling `gently_parse_list_objects_filter()` and dying
after we have modified the filter spec, we simply do so beforehand. Like
this we don't allocate the buffer in the error case, which makes the
reported leak go away.

It's not pretty, but it manages to make t6112 leak free.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jan 6, 2025
There's a race with LSan when spawning threads and one of the threads
calls die(). We worked around one such problem with index-pack in the
previous commit, but it exists in git-grep, too. You can see it with:

  make SANITIZE=leak THREAD_BARRIER_PTHREAD=YesOnLinux
  cd t
  ./t0003-attributes.sh --stress

which fails pretty quickly with:

  ==git==4096424==ERROR: LeakSanitizer: detected memory leaks

  Direct leak of 32 byte(s) in 1 object(s) allocated from:
      #0 0x7f906de14556 in realloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:98
      #1 0x7f906dc9d2c1 in __pthread_getattr_np nptl/pthread_getattr_np.c:180
      #2 0x7f906de2500d in __sanitizer::GetThreadStackTopAndBottom(bool, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:150
      #3 0x7f906de25187 in __sanitizer::GetThreadStackAndTls(bool, unsigned long*, unsigned long*, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:614
      #4 0x7f906de17d18 in __lsan::ThreadStart(unsigned int, unsigned long long, __sanitizer::ThreadType) ../../../../src/libsanitizer/lsan/lsan_posix.cpp:53
      #5 0x7f906de143a9 in ThreadStartFunc<false> ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:431
      #6 0x7f906dc9bf51 in start_thread nptl/pthread_create.c:447
      #7 0x7f906dd1a677 in __clone3 ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78

As with the previous commit, we can fix this by inserting a barrier that
makes sure all threads have finished their setup before continuing. But
there's one twist in this case: the thread which calls die() is not one
of the worker threads, but the main thread itself!

So we need the main thread to wait in the barrier, too, until all
threads have gotten to it. And thus we initialize the barrier for
num_threads+1, to account for all of the worker threads plus the main
one.

If we then test as above, t0003 should run indefinitely.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jan 6, 2025
In 1b9e9be (csum-file.c: use unsafe SHA-1 implementation when
available, 2024-09-26) we have converted our `struct hashfile` to use
the unsafe SHA1 backend, which results in a significant speedup. One
needs to be careful with how to use that structure now though because
callers need to consistently use either the safe or unsafe variants of
SHA1, as otherwise one can easily trigger corruption.

As it turns out, we have one inconsistent usage in our tree because we
directly initialize `struct hashfile_checkpoint::ctx` with the safe
variant of SHA1, but end up writing to that context with the unsafe
ones. This went unnoticed so far because our CI systems do not exercise
different hash functions for these two backends, and consequently safe
and unsafe variants are equivalent. But when using SHA1DC as safe and
OpenSSL as unsafe backend this leads to a crash an t1050:

    ++ git -c core.compression=0 add large1
    AddressSanitizer:DEADLYSIGNAL
    =================================================================
    ==1367==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000040 (pc 0x7ffff7a01a99 bp 0x507000000db0 sp 0x7fffffff5690 T0)
    ==1367==The signal is caused by a READ memory access.
    ==1367==Hint: address points to the zero page.
        #0 0x7ffff7a01a99 in EVP_MD_CTX_copy_ex (/nix/store/h1ydpxkw9qhjdxjpic1pdc2nirggyy6f-openssl-3.3.2/lib/libcrypto.so.3+0x201a99) (BuildId: 41746a580d39075fc85e8c8065b6c07fb34e97d4)
        #1 0x555555ddde56 in openssl_SHA1_Clone ../sha1/openssl.h:40:2
        #2 0x555555dce2fc in git_hash_sha1_clone_unsafe ../object-file.c:123:2
        #3 0x555555c2d5f8 in hashfile_checkpoint ../csum-file.c:211:2
        #4 0x555555b9905d in deflate_blob_to_pack ../bulk-checkin.c:286:4
        #5 0x555555b98ae9 in index_blob_bulk_checkin ../bulk-checkin.c:362:15
        #6 0x555555ddab62 in index_blob_stream ../object-file.c:2756:9
        #7 0x555555dda420 in index_fd ../object-file.c:2778:9
        #8 0x555555ddad76 in index_path ../object-file.c:2796:7
        #9 0x555555e947f3 in add_to_index ../read-cache.c:771:7
        #10 0x555555e954a4 in add_file_to_index ../read-cache.c:804:9
        #11 0x5555558b5c39 in add_files ../builtin/add.c:355:7
        #12 0x5555558b412e in cmd_add ../builtin/add.c:578:18
        #13 0x555555b1f493 in run_builtin ../git.c:480:11
        #14 0x555555b1bfef in handle_builtin ../git.c:740:9
        #15 0x555555b1e6f4 in run_argv ../git.c:807:4
        #16 0x555555b1b87a in cmd_main ../git.c:947:19
        #17 0x5555561649e6 in main ../common-main.c:64:11
        #18 0x7ffff742a1fb in __libc_start_call_main (/nix/store/65h17wjrrlsj2rj540igylrx7fqcd6vq-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: bf320110569c8ec2425e9a0c5e4eb7e97f1fb6e4)
        #19 0x7ffff742a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/65h17wjrrlsj2rj540igylrx7fqcd6vq-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: bf320110569c8ec2425e9a0c5e4eb7e97f1fb6e4)
        #20 0x555555772c84 in _start (git+0x21ec84)

    ==1367==Register values:
    rax = 0x0000511000001080  rbx = 0x0000000000000000  rcx = 0x000000000000000c  rdx = 0x0000000000000000
    rdi = 0x0000000000000000  rsi = 0x0000507000000db0  rbp = 0x0000507000000db0  rsp = 0x00007fffffff5690
     r8 = 0x0000000000000000   r9 = 0x0000000000000000  r10 = 0x0000000000000000  r11 = 0x00007ffff7a01a30
    r12 = 0x0000000000000000  r13 = 0x00007fffffff6b38  r14 = 0x00007ffff7ffd000  r15 = 0x00005555563b9910
    AddressSanitizer can not provide additional info.
    SUMMARY: AddressSanitizer: SEGV (/nix/store/h1ydpxkw9qhjdxjpic1pdc2nirggyy6f-openssl-3.3.2/lib/libcrypto.so.3+0x201a99) (BuildId: 41746a580d39075fc85e8c8065b6c07fb34e97d4) in EVP_MD_CTX_copy_ex
    ==1367==ABORTING
    ./test-lib.sh: line 1023:  1367 Aborted                 git $config add large1
    error: last command exited with $?=134
    not ok 4 - add with -c core.compression=0

Fix the issue by using the unsafe variant instead.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jan 6, 2025
Same as with the preceding commit, git-fast-import(1) is using the safe
variant to initialize a hashfile checkpoint. This leads to a segfault
when passing the checkpoint into the hashfile subsystem because it would
use the unsafe variants instead:

    ++ git --git-dir=R/.git fast-import --big-file-threshold=1
    AddressSanitizer:DEADLYSIGNAL
    =================================================================
    ==577126==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000040 (pc 0x7ffff7a01a99 bp 0x5070000009c0 sp 0x7fffffff5b30 T0)
    ==577126==The signal is caused by a READ memory access.
    ==577126==Hint: address points to the zero page.
        #0 0x7ffff7a01a99 in EVP_MD_CTX_copy_ex (/nix/store/h1ydpxkw9qhjdxjpic1pdc2nirggyy6f-openssl-3.3.2/lib/libcrypto.so.3+0x201a99) (BuildId: 41746a580d39075fc85e8c8065b6c07fb34e97d4)
        #1 0x555555ddde56 in openssl_SHA1_Clone ../sha1/openssl.h:40:2
        #2 0x555555dce2fc in git_hash_sha1_clone_unsafe ../object-file.c:123:2
        #3 0x555555c2d5f8 in hashfile_checkpoint ../csum-file.c:211:2
        #4 0x5555559647d1 in stream_blob ../builtin/fast-import.c:1110:2
        #5 0x55555596247b in parse_and_store_blob ../builtin/fast-import.c:2031:3
        #6 0x555555967f91 in file_change_m ../builtin/fast-import.c:2408:5
        #7 0x55555595d8a2 in parse_new_commit ../builtin/fast-import.c:2768:4
        #8 0x55555595bb7a in cmd_fast_import ../builtin/fast-import.c:3614:4
        #9 0x555555b1f493 in run_builtin ../git.c:480:11
        #10 0x555555b1bfef in handle_builtin ../git.c:740:9
        #11 0x555555b1e6f4 in run_argv ../git.c:807:4
        #12 0x555555b1b87a in cmd_main ../git.c:947:19
        #13 0x5555561649e6 in main ../common-main.c:64:11
        #14 0x7ffff742a1fb in __libc_start_call_main (/nix/store/65h17wjrrlsj2rj540igylrx7fqcd6vq-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: bf320110569c8ec2425e9a0c5e4eb7e97f1fb6e4)
        #15 0x7ffff742a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/65h17wjrrlsj2rj540igylrx7fqcd6vq-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: bf320110569c8ec2425e9a0c5e4eb7e97f1fb6e4)
        #16 0x555555772c84 in _start (git+0x21ec84)

    ==577126==Register values:
    rax = 0x0000511000000cc0  rbx = 0x0000000000000000  rcx = 0x000000000000000c  rdx = 0x0000000000000000
    rdi = 0x0000000000000000  rsi = 0x00005070000009c0  rbp = 0x00005070000009c0  rsp = 0x00007fffffff5b30
     r8 = 0x0000000000000000   r9 = 0x0000000000000000  r10 = 0x0000000000000000  r11 = 0x00007ffff7a01a30
    r12 = 0x0000000000000000  r13 = 0x00007fffffff6b60  r14 = 0x00007ffff7ffd000  r15 = 0x00005555563b9910
    AddressSanitizer can not provide additional info.
    SUMMARY: AddressSanitizer: SEGV (/nix/store/h1ydpxkw9qhjdxjpic1pdc2nirggyy6f-openssl-3.3.2/lib/libcrypto.so.3+0x201a99) (BuildId: 41746a580d39075fc85e8c8065b6c07fb34e97d4) in EVP_MD_CTX_copy_ex
    ==577126==ABORTING
    ./test-lib.sh: line 1039: 577126 Aborted                 git --git-dir=R/.git fast-import --big-file-threshold=1 < input
    error: last command exited with $?=134
    not ok 167 - R: blob bigger than threshold

The segfault is only exposed in case the unsafe and safe backends are
different from one another.

Fix the issue by initializing the context with the unsafe SHA1 variant.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Jan 6, 2025
Our CI jobs sometimes see false positive leaks like this:

        =================================================================
        ==3904583==ERROR: LeakSanitizer: detected memory leaks

        Direct leak of 32 byte(s) in 1 object(s) allocated from:
            #0 0x7fa790d01986 in __interceptor_realloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:98
            #1 0x7fa790add769 in __pthread_getattr_np nptl/pthread_getattr_np.c:180
            #2 0x7fa790d117c5 in __sanitizer::GetThreadStackTopAndBottom(bool, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:150
            #3 0x7fa790d11957 in __sanitizer::GetThreadStackAndTls(bool, unsigned long*, unsigned long*, unsigned long*, unsigned long*) ../../../../src/libsanitizer/sanitizer_common/sanitizer_linux_libcdep.cpp:598
            #4 0x7fa790d03fe8 in __lsan::ThreadStart(unsigned int, unsigned long long, __sanitizer::ThreadType) ../../../../src/libsanitizer/lsan/lsan_posix.cpp:51
            #5 0x7fa790d013fd in __lsan_thread_start_func ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:440
            #6 0x7fa790adc3eb in start_thread nptl/pthread_create.c:444
            #7 0x7fa790b5ca5b in clone3 ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81

This is not a leak in our code, but appears to be a race between one
thread calling exit() while another one is in LSan's stack setup code.
You can reproduce it easily by running t0003 or t5309 with --stress
(these trigger it because of the threading in git-grep and index-pack
respectively).

This may be a bug in LSan, but regardless of whether it is eventually
fixed, it is useful to work around it so that we stop seeing these false
positives.

We can recognize it by the mention of the sanitizer functions in the
DEDUP_TOKEN line. With this patch, the scripts mentioned above should
run with --stress indefinitely.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Feb 22, 2025
When trying to create a Unix socket in a path that exceeds the maximum
socket name length we try to first change the directory into the parent
folder before creating the socket to reduce the length of the name. When
this fails we error out of `unix_sockaddr_init()` with an error code,
which indicates to the caller that the context has not been initialized.
Consequently, they don't release that context.

This leads to a memory leak: when we have already populated the context
with the original directory that we need to chdir(3p) back into, but
then the chdir(3p) into the socket's parent directory fails, then we
won't release the original directory's path. The leak is exposed by
t0301, but only when running tests in a directory hierarchy whose path
is long enough to make the socket name length exceed the maximum socket
name length:

    Direct leak of 129 byte(s) in 1 object(s) allocated from:
        #0 0x5555555e85c6 in realloc.part.0 lsan_interceptors.cpp.o
        #1 0x55555590e3d6 in xrealloc ../wrapper.c:140:8
        #2 0x5555558c8fc6 in strbuf_grow ../strbuf.c:114:2
        #3 0x5555558cacab in strbuf_getcwd ../strbuf.c:605:3
        #4 0x555555923ff6 in unix_sockaddr_init ../unix-socket.c:65:7
        #5 0x555555923e42 in unix_stream_connect ../unix-socket.c:84:6
        #6 0x55555562a984 in send_request ../builtin/credential-cache.c:46:11
        #7 0x55555562a89e in do_cache ../builtin/credential-cache.c:108:6
        #8 0x55555562a655 in cmd_credential_cache ../builtin/credential-cache.c:178:3
        #9 0x555555700547 in run_builtin ../git.c:480:11
        #10 0x5555556ff0e0 in handle_builtin ../git.c:740:9
        #11 0x5555556ffee8 in run_argv ../git.c:807:4
        #12 0x5555556fee6b in cmd_main ../git.c:947:19
        #13 0x55555593f689 in main ../common-main.c:64:11
        #14 0x7ffff7a2a1fb in __libc_start_call_main (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #15 0x7ffff7a2a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #16 0x5555555ad1d4 in _start (git+0x591d4)

    DEDUP_TOKEN: ___interceptor_realloc.part.0--xrealloc--strbuf_grow--strbuf_getcwd--unix_sockaddr_init--unix_stream_connect--send_request--do_cache--cmd_credential_cache--run_builtin--handle_builtin--run_argv--cmd_main--main--__libc_start_call_main--__libc_start_main@GLIBC_2.2.5--_start
    SUMMARY: LeakSanitizer: 129 byte(s) leaked in 1 allocation(s).

Fix this leak.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
derrickstolee pushed a commit that referenced this pull request Feb 22, 2025
We don't free the result of `remote_default_branch()`, leading to a
memory leak. This leak is exposed by t9211, but only when run with Meson
with the `-Db_sanitize=leak` option:

    Direct leak of 5 byte(s) in 1 object(s) allocated from:
        #0 0x5555555cfb93 in malloc (scalar+0x7bb93)
        #1 0x5555556b05c2 in do_xmalloc ../wrapper.c:55:8
        #2 0x5555556b06c4 in do_xmallocz ../wrapper.c:89:8
        #3 0x5555556b0656 in xmallocz ../wrapper.c:97:9
        #4 0x5555556b0728 in xmemdupz ../wrapper.c:113:16
        #5 0x5555556b07a7 in xstrndup ../wrapper.c:119:9
        #6 0x5555555d3a4b in remote_default_branch ../scalar.c:338:14
        #7 0x5555555d20e6 in cmd_clone ../scalar.c:493:28
        #8 0x5555555d196b in cmd_main ../scalar.c:992:14
        #9 0x5555557c4059 in main ../common-main.c:64:11
        #10 0x7ffff7a2a1fb in __libc_start_call_main (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a1fb) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #11 0x7ffff7a2a2b8 in __libc_start_main@GLIBC_2.2.5 (/nix/store/h7zcxabfxa7v5xdna45y2hplj31ncf8a-glibc-2.40-36/lib/libc.so.6+0x2a2b8) (BuildId: 0a855678aa0cb573cecbb2bcc73ab8239ec472d0)
        #12 0x555555592054 in _start (scalar+0x3e054)

    DEDUP_TOKEN: __interceptor_malloc--do_xmalloc--do_xmallocz--xmallocz--xmemdupz--xstrndup--remote_default_branch--cmd_clone--cmd_main--main--__libc_start_call_main--__libc_start_main@GLIBC_2.2.5--_start
    SUMMARY: LeakSanitizer: 5 byte(s) leaked in 1 allocation(s).

As the `branch` variable may contain a string constant obtained from
parsing command line arguments we cannot free the leaking variable
directly. Instead, introduce a new `branch_to_free` variable that only
ever gets assigned the allocated string and free that one to plug the
leak.

It is unclear why the leak isn't flagged when running the test via our
Makefile.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
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