ASan global-buffer-overflow src/stb_image.h:1913 in stbi__extend_receive

[fgeek]

libsixel-global-buffer-overflow-stb_image.h-1913-stbi__extend_receive-002.png.zip (SHA1: 88464b3bce4bcb8d3be434470dd6500d756d93dd)
Tested commit: 2df6437
Credit: Henri Salo
Tools: american fuzzy lop 2.52b, afl-utils
Notes: Looks similar to #70

./bin/img2sixel -o test libsixel-global-buffer-overflow-stb_image.h-1913-stbi__extend_receive-002.png
================================================================
==17472==ERROR: AddressSanitizer: global-buffer-overflow on address 0x7fe3abc83d60 at pc 0x7fe3abbeb7eb bp 0x7fffc1b991f0 sp 0x7fffc1b991e8
READ of size 4 at 0x7fe3abc83d60 thread T0
    #0 0x7fe3abbeb7ea in stbi__extend_receive /home/hsalo/src/libsixel/src/stb_image.h:1913
    #1 0x7fe3abbeb7ea in stbi__jpeg_decode_block_prog_dc /home/hsalo/src/libsixel/src/stb_image.h:2020
    #2 0x7fe3abbeb7ea in stbi__parse_entropy_coded_data /home/hsalo/src/libsixel/src/stb_image.h:2793
    #3 0x7fe3abc1ccfb in stbi__decode_jpeg_image /home/hsalo/src/libsixel/src/stb_image.h:3132
    #4 0x7fe3abc1ccfb in load_jpeg_image /home/hsalo/src/libsixel/src/stb_image.h:3584
    #5 0x7fe3abc1ccfb in stbi__jpeg_load /home/hsalo/src/libsixel/src/stb_image.h:3741
    #6 0x7fe3abc1ccfb in stbi__load_main /home/hsalo/src/libsixel/src/stb_image.h:980
    #7 0x7fe3abc34c84 in stbi__load_and_postprocess_8bit /home/hsalo/src/libsixel/src/stb_image.h:1090
    #8 0x7fe3abc38fbd in load_with_builtin /home/hsalo/src/libsixel/src/loader.c:882
    #9 0x7fe3abc46180 in sixel_helper_load_image_file /home/hsalo/src/libsixel/src/loader.c:1352
    #10 0x7fe3abc66433 in sixel_encoder_encode /home/hsalo/src/libsixel/src/encoder.c:1737
    #11 0x55b60d16eb2f in main /home/hsalo/src/libsixel/converters/img2sixel.c:457
    #12 0x7fe3aadf02e0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202e0)
    #13 0x55b60d16ede9 in _start (/home/hsalo/builds/libsixel/2df64373e58c4f48fbb72032a66473e71fc2a6ce/bin/img2sixel+0x2de9)

0x7fe3abc83d60 is located 32 bytes to the left of global variable 'stbi__bmask' defined in 'stb_image.h:1844:27' (0x7fe3abc83d80) of size 68
0x7fe3abc83d60 is located 0 bytes to the right of global variable 'stbi__jbias' defined in 'stb_image.h:1897:18' (0x7fe3abc83d20) of size 64
SUMMARY: AddressSanitizer: global-buffer-overflow /home/hsalo/src/libsixel/src/stb_image.h:1913 in stbi__extend_receive
Shadow bytes around the buggy address:
  0x0ffcf5788750: 00 00 00 00 f9 f9 f9 f9 00 00 00 00 00 00 00 00
  0x0ffcf5788760: 00 00 00 00 00 00 00 00 f9 f9 f9 f9 00 00 00 00
  0x0ffcf5788770: 00 00 00 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9
  0x0ffcf5788780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 04
  0x0ffcf5788790: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 07 f9 f9
=>0x0ffcf57887a0: f9 f9 f9 f9 00 00 00 00 00 00 00 00[f9]f9 f9 f9
  0x0ffcf57887b0: 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9 f9 f9 f9
  0x0ffcf57887c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ffcf57887d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ffcf57887e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0ffcf57887f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==17472==ABORTING

[fgeek]

@saitoha Fix confirmed. Sorry it took some time from me. This got lost in the void. Can you merge that branch to master and close this issue report, thank you?