heap-buffer-overflow in img_load_from_data

[tianxiaogu]

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==30322==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000000f2 at pc 0x0000005bdf2d bp 0x7ffe187d5be0 sp 0x7ffe187d5bd8
WRITE of size 2 at 0x6020000000f2 thread T0
    #0 0x5bdf2c in img_load_from_data /home/t/Projects/afl/fuzzing-experiments/subjects/catimg/src/sh_image.c:174:52
    #1 0x5beadd in img_load_from_file /home/t/Projects/afl/fuzzing-experiments/subjects/catimg/src/sh_image.c:190:9
    #2 0x52836c in main /home/t/Projects/afl/fuzzing-experiments/subjects/catimg/src/catimg.c:115:9
    #3 0x7f5a606bab96 in __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/../csu/libc-start.c:310
    #4 0x41bbe9 in _start (/home/t/Projects/afl/fuzzing-experiments/subjects/catimg/bin/catimg+0x41bbe9)

0x6020000000f2 is located 0 bytes to the right of 2-byte region [0x6020000000f0,0x6020000000f2)
allocated by thread T0 here:
    #0 0x4e5f17 in malloc /home/t/Projects/lldb-testing/llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:146
    #1 0x5bd84e in img_load_from_data /home/t/Projects/afl/fuzzing-experiments/subjects/catimg/src/sh_image.c:145:51

SUMMARY: AddressSanitizer: heap-buffer-overflow /home/t/Projects/afl/fuzzing-experiments/subjects/catimg/src/sh_image.c:174:52 in img_load_from_data
Shadow bytes around the buggy address:
  0x0c047fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c047fff8000: fa fa fd fa fa fa fd fd fa fa fd fd fa fa fd fa
=>0x0c047fff8010: fa fa fd fa fa fa fd fa fa fa fd fd fa fa[02]fa
  0x0c047fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8060: 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
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  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
  Shadow gap:              cc
==30322==ABORTING

[posva]

Thanks for posting this but these are all related to the external lib that load images. I accept prs for fixing these but I don't have time to fix it myself 🙂