Hi, OSS-Fuzz found https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=56134 introduced in fda09f5f188fb173b2123815be71ca4647a8adfb but for some reason it wasn't delivered to the mailing list. I opened https://github.com/google/oss-fuzz/issues/9755 to figure out what went wrong there but until then below is the full backtrace: ``` ==2272==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x5fb3c7 in check_section /src/elfutils/libdw/dwarf_begin_elf.c:265:7 #1 0x5f8d3e in global_read /src/elfutils/libdw/dwarf_begin_elf.c:444:14 #2 0x5f8d3e in dwarf_begin_elf /src/elfutils/libdw/dwarf_begin_elf.c:595:9 #3 0x53f28c in load_dw /src/elfutils/libdwfl/dwfl_module_getdwarf.c:1341:13 #4 0x53c5b9 in find_dw /src/elfutils/libdwfl/dwfl_module_getdwarf.c:1391:16 #5 0x53c5b9 in dwfl_module_getdwarf /src/elfutils/libdwfl/dwfl_module_getdwarf.c:1446:3 #6 0x534b72 in LLVMFuzzerTestOneInput /src/fuzz-libdwfl.c:54:3 #7 0x43dcf3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:611:15 #8 0x429452 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:324:6 #9 0x42ecfc in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:860:9 #10 0x458232 in main /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerMain.cpp:20:10 #11 0x7fe0978dd0b2 in __libc_start_main /build/glibc-eX1tMB/glibc-2.31/csu/libc-start.c:308:16 #12 0x41f61d in _start Uninitialized value was created by a heap allocation #0 0x4e2310 in __interceptor_malloc /src/llvm-project/compiler-rt/lib/msan/msan_interceptors.cpp:895:3 #1 0x6b9935 in convert_data /src/elfutils/libelf/elf_getdata.c:166:24 #2 0x6b9935 in __libelf_set_data_list_rdlock /src/elfutils/libelf/elf_getdata.c:455:7 #3 0x6ba571 in __elf_getdata_rdlock /src/elfutils/libelf/elf_getdata.c:562:5 #4 0x6ba6cd in elf_getdata /src/elfutils/libelf/elf_getdata.c:580:12 #5 0x5faec7 in check_section /src/elfutils/libdw/dwarf_begin_elf.c:246:20 #6 0x5f8d3e in global_read /src/elfutils/libdw/dwarf_begin_elf.c:444:14 #7 0x5f8d3e in dwarf_begin_elf /src/elfutils/libdw/dwarf_begin_elf.c:595:9 #8 0x53f28c in load_dw /src/elfutils/libdwfl/dwfl_module_getdwarf.c:1341:13 #9 0x53c5b9 in find_dw /src/elfutils/libdwfl/dwfl_module_getdwarf.c:1391:16 #10 0x53c5b9 in dwfl_module_getdwarf /src/elfutils/libdwfl/dwfl_module_getdwarf.c:1446:3 #11 0x534b72 in LLVMFuzzerTestOneInput /src/fuzz-libdwfl.c:54:3 #12 0x43dcf3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:611:15 #13 0x429452 in fuzzer::RunOneTest(fuzzer::Fuzzer*, char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:324:6 #14 0x42ecfc in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:860:9 #15 0x458232 in main /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerMain.cpp:20:10 #16 0x7fe0978dd0b2 in __libc_start_main /build/glibc-eX1tMB/glibc-2.31/csu/libc-start.c:308:16 SUMMARY: MemorySanitizer: use-of-uninitialized-value (/mnt/scratch0/clusterfuzz/bot/builds/clusterfuzz-builds_elfutils_3ee01cb67db1a71e7adeb7f3f14722ea62f13cd5/revisions/fuzz-libdwfl+0x5fb3c7) ```
It can be reproduced with `readelf` and `valgrind` ``` wget -O OSS-FUZZ-56134 'https://oss-fuzz.com/download?testcase_id=6724057145147392' LD_LIBRARY_PATH="$(pwd)/libdw:$(pwd)/libelf" DEBUGINFOD_URLS= valgrind --track-origins=yes ./src/readelf -w OSS-FUZZ-56134 ==1373524== Memcheck, a memory error detector ==1373524== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al. ==1373524== Using Valgrind-3.19.0 and LibVEX; rerun with -h for copyright info ==1373524== Command: ./src/readelf -w OSS-FUZZ-56134 ==1373524== ==1373524== Conditional jump or move depends on uninitialised value(s) ==1373524== at 0x4887EAB: check_section (dwarf_begin_elf.c:265) ==1373524== by 0x48885EF: global_read (dwarf_begin_elf.c:444) ==1373524== by 0x48885EF: dwarf_begin_elf (dwarf_begin_elf.c:595) ==1373524== by 0x48A9F0C: load_dw (dwfl_module_getdwarf.c:1341) ==1373524== by 0x48AA0D0: find_dw (dwfl_module_getdwarf.c:1391) ==1373524== by 0x48AA0D0: dwfl_module_getdwarf (dwfl_module_getdwarf.c:1446) ==1373524== by 0x411109: print_debug (readelf.c:11467) ==1373524== by 0x413A31: process_elf_file (readelf.c:1062) ==1373524== by 0x4148BC: process_dwflmod (readelf.c:818) ==1373524== by 0x48A7F20: dwfl_getmodules (dwfl_getmodules.c:86) ==1373524== by 0x40954A: process_file (readelf.c:926) ==1373524== by 0x404D0E: main (readelf.c:395) ==1373524== Uninitialised value was created by a heap allocation ==1373524== at 0x484586F: malloc (vg_replace_malloc.c:381) ==1373524== by 0x48FEA25: convert_data (elf_getdata.c:166) ==1373524== by 0x48FEA25: __libelf_set_data_list_rdlock (elf_getdata.c:455) ==1373524== by 0x48FEC17: __elf_getdata_rdlock (elf_getdata.c:562) ==1373524== by 0x4887E6F: check_section (dwarf_begin_elf.c:246) ==1373524== by 0x48885EF: global_read (dwarf_begin_elf.c:444) ==1373524== by 0x48885EF: dwarf_begin_elf (dwarf_begin_elf.c:595) ==1373524== by 0x48A9F0C: load_dw (dwfl_module_getdwarf.c:1341) ==1373524== by 0x48AA0D0: find_dw (dwfl_module_getdwarf.c:1391) ==1373524== by 0x48AA0D0: dwfl_module_getdwarf (dwfl_module_getdwarf.c:1446) ==1373524== by 0x411109: print_debug (readelf.c:11467) ==1373524== by 0x413A31: process_elf_file (readelf.c:1062) ==1373524== by 0x4148BC: process_dwflmod (readelf.c:818) ==1373524== by 0x48A7F20: dwfl_getmodules (dwfl_getmodules.c:86) ==1373524== by 0x40954A: process_file (readelf.c:926) ==1373524== ./src/readelf: cannot get debug context descriptor: No DWARF information found ``` Thanks, Evgeny Vereshchagin
