libxml2 – xmlDictAddString Heap Buffer Overread
Source: https://code.google.com/p/google-security-research/issues/detail?id=637 The following crash due to a heap-based out-of-bounds memory read can be observed in an ASAN build of latest stable libxml2 (2.9.3, released 4 days ago), by feeding a malformed file to xmllint ("$ ./xmllint --html /path/to/file"): --- cut --- ==25920==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x631000010810 at pc 0x0000004a2f25 bp 0x7ffc81805ae0 sp 0x7ffc81805290 READ of size 73661 at 0x631000010810 thread T0 #0 0x4a2f24 in __asan_memcpy llvm/projects/compiler-rt/lib/asan/asan_interceptors.cc:393 #1 0xd026b2 in xmlDictAddString libxml2-2.9.3/dict.c:285:5 #2 0xd009e8 in xmlDictLookup libxml2-2.9.3/dict.c:926:11 #3 0x806e4d in htmlParseNameComplex libxml2-2.9.3/HTMLparser.c:2517:12 #4 0x7cc29d in htmlParseName libxml2-2.9.3/HTMLparser.c:2483:12 #5 0x7ca6f1 in htmlParseEntityRef libxml2-2.9.3/HTMLparser.c:2682:16 #6 0x820a0d in htmlParseReference libxml2-2.9.3/HTMLparser.c:4044:8 #7 0x7df716 in htmlParseContentInternal libxml2-2.9.3/HTMLparser.c:4619:3 #8 0x7e2f0f in htmlParseDocument libxml2-2.9.3/HTMLparser.c:4769:5 #9 0x802c55 in htmlDoRead libxml2-2.9.3/HTMLparser.c:6741:5 #10 0x8030b6 in htmlReadFile libxml2-2.9.3/HTMLparser.c:6799:13 #11 0x4f47a5 in parseAndPrintFile libxml2-2.9.3/xmllint.c:2248:8 #12 0x4ebe8f in main libxml2-2.9.3/xmllint.c:3759:7 0x631000010810 is located 0 bytes to the right of 65552-byte region [0x631000000800,0x631000010810) allocated by thread T0 here: #0 0x4b8ef0 in realloc llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:61 #1 0xa079a5 in xmlBufGrowInternal libxml2-2.9.3/buf.c:486:23 #2 0xa06722 in xmlBufGrow libxml2-2.9.3/buf.c:515:11 #3 0x72fef4 in xmlParserInputBufferGrow libxml2-2.9.3/xmlIO.c:3326:9 #4 0x543b22 in xmlParserInputGrow libxml2-2.9.3/parserInternals.c:320:8 #5 0x8067f4 in htmlParseNameComplex libxml2-2.9.3/HTMLparser.c:2511:6 #6 0x7cc29d in htmlParseName libxml2-2.9.3/HTMLparser.c:2483:12 #7 0x7ca6f1 in htmlParseEntityRef libxml2-2.9.3/HTMLparser.c:2682:16 #8 0x820a0d in htmlParseReference libxml2-2.9.3/HTMLparser.c:4044:8 #9 0x7df716 in htmlParseContentInternal libxml2-2.9.3/HTMLparser.c:4619:3 #10 0x7e2f0f in htmlParseDocument libxml2-2.9.3/HTMLparser.c:4769:5 #11 0x802c55 in htmlDoRead libxml2-2.9.3/HTMLparser.c:6741:5 #12 0x8030b6 in htmlReadFile libxml2-2.9.3/HTMLparser.c:6799:13 #13 0x4f47a5 in parseAndPrintFile libxml2-2.9.3/xmllint.c:2248:8 #14 0x4ebe8f in main libxml2-2.9.3/xmllint.c:3759:7 SUMMARY: AddressSanitizer: heap-buffer-overflow llvm/projects/compiler-rt/lib/asan/asan_interceptors.cc:393 in __asan_memcpy Shadow bytes around the buggy address: 0x0c627fffa0b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c627fffa0c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c627fffa0d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c627fffa0e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x0c627fffa0f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 =>0x0c627fffa100: 00 00[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c627fffa110: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c627fffa120: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c627fffa130: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c627fffa140: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x0c627fffa150: 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 Heap right redzone: fb Freed heap region: fd Stack left redzone: f1 Stack mid redzone: f2 Stack right redzone: f3 Stack partial redzone: f4 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 ==25920==ABORTING --- cut --- The crash was reported at https://bugzilla.gnome.org/show_bug.cgi?id=758605. Attached is an XML file which triggers the crash. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/39491.zip |