elfutils: add and expand library fuzzers (#7395)

* elfutils: make name more appropriate

* elfutils: update libelf fuzzer

* elfutils: add fuzz-libdwfl

* elfutils: nits

* elfutils: fix build

projects/elfutils/build.sh

@@ -93,11 +93,20 @@ $CXX $CXXFLAGS $LIB_FUZZING_ENGINE fuzz-dwfl-core.o \
 $CC $CFLAGS \
   -D_GNU_SOURCE -DHAVE_CONFIG_H \
   -I. -I./lib -I./libelf -I./libebl -I./libdw -I./libdwelf -I./libdwfl -I./libasm \
-  -c "$SRC/fuzz-elf-get-sections.c" -o fuzz-elf-get-sections.o
-$CXX $CXXFLAGS $LIB_FUZZING_ENGINE fuzz-elf-get-sections.o \
+  -c "$SRC/fuzz-libelf.c" -o fuzz-libelf.o
+$CXX $CXXFLAGS $LIB_FUZZING_ENGINE fuzz-libelf.o \
 	./libasm/libasm.a ./libebl/libebl.a ./backends/libebl_backends.a ./libcpu/libcpu.a \
   ./libdw/libdw.a ./libelf/libelf.a ./lib/libeu.a -l:libz.a \
-	-o "$OUT/fuzz-elf-get-sections"
+	-o "$OUT/fuzz-libelf"
+
+$CC $CFLAGS \
+  -D_GNU_SOURCE -DHAVE_CONFIG_H \
+  -I. -I./lib -I./libelf -I./libebl -I./libdw -I./libdwelf -I./libdwfl -I./libasm \
+  -c "$SRC/fuzz-libdwfl.c" -o fuzz-libdwfl.o
+$CXX $CXXFLAGS $LIB_FUZZING_ENGINE fuzz-libdwfl.o \
+	./libasm/libasm.a ./libebl/libebl.a ./backends/libebl_backends.a ./libcpu/libcpu.a \
+  ./libdw/libdw.a ./libelf/libelf.a ./lib/libeu.a -l:libz.a \
+	-o "$OUT/fuzz-libdwfl"
 
 # Corpus
 cp "$SRC/fuzz-dwfl-core_seed_corpus.zip" "$OUT"

projects/elfutils/fuzz-libdwfl.c

@@ -0,0 +1,53 @@
+/* Copyright 2022 Google LLC
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+      http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+#include <fcntl.h>
+#include <gelf.h>
+#include <inttypes.h>
+#include <libelf.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include "libdwfl.h"
+
+static const char *debuginfo_path = "";
+static const Dwfl_Callbacks cb  = {
+  NULL,
+  dwfl_standard_find_debuginfo,
+  NULL,
+  (char **)&debuginfo_path,
+};
+
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  char filename[256];
+  sprintf(filename, "/tmp/libfuzzer.%d", getpid());
+  FILE *fp = fopen(filename, "wb");
+  if (!fp) {
+    return 0;
+  }
+  fwrite(data, size, 1, fp);
+  fclose(fp);
+
+  Dwarf_Addr bias = 0;
+  Dwfl *dwfl = dwfl_begin(&cb);
+  dwfl_report_begin(dwfl);
+
+  Dwfl_Module *mod = dwfl_report_offline(dwfl, filename, filename, -1);
+  Dwarf *res = dwfl_module_getdwarf(mod, &bias);
+
+  dwfl_end (dwfl);
+  unlink(filename);
+  return 0;
+}

projects/elfutils/fuzz-elf-get-sections.c → projects/elfutils/fuzz-libelf.c

@@ -10,7 +10,6 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-/* Inspired by the elfgetzdata.c test */
 #include <fcntl.h>
 #include <gelf.h>
 #include <inttypes.h>
@@ -21,17 +20,8 @@ limitations under the License.
 #include <sys/types.h>
 #include <unistd.h>
 
-int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
-  char filename[256];
-  sprintf(filename, "/tmp/libfuzzer.%d", getpid());
-  FILE *fp = fopen(filename, "wb");
-  if (!fp) {
-    return 0;
-  }
-  fwrite(data, size, 1, fp);
-  fclose(fp);
 
-  // Main fuzz entrypoint in objdump.c
+void fuzz_logic_one(char *filename, int compression_type) {
   (void)elf_version(EV_CURRENT);
   int fd = open(filename, O_RDONLY);
   Elf *elf = elf_begin(fd, ELF_C_READ, NULL);
@@ -50,7 +40,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
       // so it resembles the test code.
       // Compress and get data of the section
       if ((shdr->sh_flags & SHF_COMPRESSED) != 0) {
-        if (elf_compress(scn, 0, 0) >= 0) {
+        if (elf_compress(scn, compression_type, 0) >= 0) {
           elf_getdata(scn, NULL);
         }
       } else if (name != NULL) {
@@ -63,8 +53,38 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     }
     elf_end(elf);
   }
+  close(fd);
+}
 
+void fuzz_logic_twice(char *filename, int open_flags, Elf_Cmd cmd) {
+  (void)elf_version(EV_CURRENT);
+  int fd = open(filename, open_flags);
+  Elf *elf = elf_begin(fd, cmd, NULL);
+  if (elf != NULL) {
+    size_t elf_size = 0;
+    elf_rawfile(elf, &elf_size);
+    elf_end(elf);
+  }
   close(fd);
+}
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  char filename[256];
+  sprintf(filename, "/tmp/libfuzzer.%d", getpid());
+  FILE *fp = fopen(filename, "wb");
+  if (!fp) {
+    return 0;
+  }
+  fwrite(data, size, 1, fp);
+  fclose(fp);
+
+  fuzz_logic_one(filename, 0);
+  fuzz_logic_one(filename, 1);
+  fuzz_logic_twice(filename, O_RDONLY, ELF_C_READ);
+  fuzz_logic_twice(filename, O_RDONLY | O_WRONLY, ELF_C_RDWR);
+  fuzz_logic_twice(filename, O_RDONLY, ELF_C_READ_MMAP);
+  fuzz_logic_twice(filename, O_RDONLY | O_WRONLY, ELF_C_RDWR_MMAP);
+
   unlink(filename);
   return 0;
 }