avoid setting LIMIT_HEAP incorrectly since d90fb23 (included in PCRE2 10.41) #184
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zherczeg
reviewed
Dec 30, 2022
| @@ -858,7 +858,7 @@ doing traditional NFA matching (pcre2_match() and friends). */ | |||
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| typedef struct match_block { | |||
| pcre2_memctl memctl; /* For general use */ | |||
| PCRE2_SIZE heap_limit; /* As it says */ | |||
| uint32_t heap_limit; /* As it says */ | |||
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PCRE2_SIZE is 64 bit long on 64 bit systems, isn't it?
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correct, but the heap_limit value can only be lower than UINT32_MAX even if it can represent memory sizes larger than 4GB in 64-bit systems because it uses KB for units.
the main point of this change (other than making it consistent with the other references and saving a little bit of memory) is to try to get the compiler to help us in the future to detect places where similar truncations could be introduced.
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carenas
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If a LIMIT_HEAP value once converted to bytes is larger than UINT_MAX
would result in a bogus setting that could trigger a matching failure
as shown by the following:
PCRE2 version 10.42 2022-12-11
re> /(*LIMIT_HEAP=4194304)a/
data> a
Failed: error -63: heap limit exceeded
Remove the multiplication and instead keep track of the maximum heap
allowed in KB as was done originally.
Aditionally, add a check to avoid overflowing a PCRE2_SIZE while
doubling the heap used and that could result in a crash (only on
systems with a 32-bit PCRE2_SIZE and using non standard settings).
Unlike the original, this code avoids rounding the heapframes_size
to the frame_size at the allocation time, which simplifies the logic
and wasn't really needed.
Fixes: d90fb23 (Refactor match_data() to always use the heap instead
of having an initial frames vector on the stack..., 2022-07-27)
Closes: PCRE2Project#183
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Avoid the unsigned integer wrap around (triggered in most matches) and use instead an uint32_t variable to hold the heap_limit (in KiB); the following example from pcre2test built with clang's -fsanitize=unsigned-integer-overflow) :
Fixes: d90fb23 (Refactor match_data() to always use the heap instead of having an initial frames vector on the stack..., 2022-07-27