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| 1 | +Source: https://code.google.com/p/google-security-research/issues/detail?id=638 |
| 2 | + |
| 3 | +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 /path/to/file"): |
| 4 | + |
| 5 | +--- cut --- |
| 6 | +==4588==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6290000049e6 at pc 0x00000062b643 bp 0x7ffffa00f570 sp 0x7ffffa00f568 |
| 7 | +READ of size 1 at 0x6290000049e6 thread T0 |
| 8 | + #0 0x62b642 in xmlParseEndTag2 libxml2-2.9.3/parser.c:9828:13 |
| 9 | + #1 0x61d620 in xmlParseElement libxml2-2.9.3/parser.c:10238:2 |
| 10 | + #2 0x618dac in xmlParseContent libxml2-2.9.3/parser.c:10042:6 |
| 11 | + #3 0x61cc7c in xmlParseElement libxml2-2.9.3/parser.c:10215:5 |
| 12 | + #4 0x618dac in xmlParseContent libxml2-2.9.3/parser.c:10042:6 |
| 13 | + #5 0x61cc7c in xmlParseElement libxml2-2.9.3/parser.c:10215:5 |
| 14 | + #6 0x63be9b in xmlParseDocument libxml2-2.9.3/parser.c:10912:2 |
| 15 | + #7 0x672b74 in xmlDoRead libxml2-2.9.3/parser.c:15390:5 |
| 16 | + #8 0x673041 in xmlReadFile libxml2-2.9.3/parser.c:15452:13 |
| 17 | + #9 0x4f5b60 in parseAndPrintFile libxml2-2.9.3/xmllint.c:2401:9 |
| 18 | + #10 0x4ebe8f in main libxml2-2.9.3/xmllint.c:3759:7 |
| 19 | + |
| 20 | +0x6290000049e6 is located 2018 bytes to the right of 16388-byte region [0x629000000200,0x629000004204) |
| 21 | +allocated by thread T0 here: |
| 22 | + #0 0x4b8ef0 in realloc llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:61 |
| 23 | + #1 0xa079a5 in xmlBufGrowInternal libxml2-2.9.3/buf.c:486:23 |
| 24 | + #2 0xa06722 in xmlBufGrow libxml2-2.9.3/buf.c:515:11 |
| 25 | + #3 0x72fef4 in xmlParserInputBufferGrow libxml2-2.9.3/xmlIO.c:3326:9 |
| 26 | + #4 0x543b22 in xmlParserInputGrow libxml2-2.9.3/parserInternals.c:320:8 |
| 27 | + #5 0x569d10 in xmlGROW libxml2-2.9.3/parser.c:2081:5 |
| 28 | + #6 0x68208d in xmlParseNCNameComplex libxml2-2.9.3/parser.c:3499:6 |
| 29 | + #7 0x68136d in xmlParseNCName libxml2-2.9.3/parser.c:3591:12 |
| 30 | + #8 0x67d282 in xmlParseQName libxml2-2.9.3/parser.c:8859:9 |
| 31 | + #9 0x61f04d in xmlParseStartTag2 libxml2-2.9.3/parser.c:9381:17 |
| 32 | + #10 0x61a626 in xmlParseElement libxml2-2.9.3/parser.c:10129:16 |
| 33 | + #11 0x618dac in xmlParseContent libxml2-2.9.3/parser.c:10042:6 |
| 34 | + #12 0x61cc7c in xmlParseElement libxml2-2.9.3/parser.c:10215:5 |
| 35 | + #13 0x618dac in xmlParseContent libxml2-2.9.3/parser.c:10042:6 |
| 36 | + #14 0x61cc7c in xmlParseElement libxml2-2.9.3/parser.c:10215:5 |
| 37 | + #15 0x63be9b in xmlParseDocument libxml2-2.9.3/parser.c:10912:2 |
| 38 | + #16 0x672b74 in xmlDoRead libxml2-2.9.3/parser.c:15390:5 |
| 39 | + #17 0x673041 in xmlReadFile libxml2-2.9.3/parser.c:15452:13 |
| 40 | + #18 0x4f5b60 in parseAndPrintFile libxml2-2.9.3/xmllint.c:2401:9 |
| 41 | + #19 0x4ebe8f in main libxml2-2.9.3/xmllint.c:3759:7 |
| 42 | + |
| 43 | +SUMMARY: AddressSanitizer: heap-buffer-overflow libxml2-2.9.3/parser.c:9828:13 in xmlParseEndTag2 |
| 44 | +Shadow bytes around the buggy address: |
| 45 | + 0x0c527fff88e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 46 | + 0x0c527fff88f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 47 | + 0x0c527fff8900: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 48 | + 0x0c527fff8910: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 49 | + 0x0c527fff8920: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 50 | +=>0x0c527fff8930: fa fa fa fa fa fa fa fa fa fa fa fa[fa]fa fa fa |
| 51 | + 0x0c527fff8940: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 52 | + 0x0c527fff8950: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 53 | + 0x0c527fff8960: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 54 | + 0x0c527fff8970: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 55 | + 0x0c527fff8980: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa |
| 56 | +Shadow byte legend (one shadow byte represents 8 application bytes): |
| 57 | + Addressable: 00 |
| 58 | + Partially addressable: 01 02 03 04 05 06 07 |
| 59 | + Heap left redzone: fa |
| 60 | + Heap right redzone: fb |
| 61 | + Freed heap region: fd |
| 62 | + Stack left redzone: f1 |
| 63 | + Stack mid redzone: f2 |
| 64 | + Stack right redzone: f3 |
| 65 | + Stack partial redzone: f4 |
| 66 | + Stack after return: f5 |
| 67 | + Stack use after scope: f8 |
| 68 | + Global redzone: f9 |
| 69 | + Global init order: f6 |
| 70 | + Poisoned by user: f7 |
| 71 | + Container overflow: fc |
| 72 | + Array cookie: ac |
| 73 | + Intra object redzone: bb |
| 74 | + ASan internal: fe |
| 75 | + Left alloca redzone: ca |
| 76 | + Right alloca redzone: cb |
| 77 | +==4588==ABORTING |
| 78 | +--- cut --- |
| 79 | + |
| 80 | +The crash was reported at https://bugzilla.gnome.org/show_bug.cgi?id=758589. Attached is an XML file which triggers the crash. |
| 81 | + |
| 82 | + |
| 83 | +Proof of Concept: |
| 84 | +https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/sploits/39492.zip |
| 85 | + |
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