Heap-buffer-overflow in scale.c:214

[chameleon10712]

Description

Heap-buffer-overflow in scale.c:214 scale_without_resampling() (SEGV)

Case 1

Normal build

$ /home/oceane/libsixel_norm/libsixel/build/bin/img2sixel -r nearest  -h 3 ./poc_min
Segmentation fault

with ASan

$  /home/oceane/libsixel_asan/build_asan/bin/img2sixel -r nearest  -h 3 ./poc_min
AddressSanitizer:DEADLYSIGNAL
=================================================================
==2489639==ERROR: AddressSanitizer: SEGV on unknown address 0x7fc5ba7376cb (pc 0x7fc5bebe78da bp 0x000000000000 sp 0x7ffe4e0c2430 T0)
==2489639==The signal is caused by a READ memory access.
    #0 0x7fc5bebe78d9 in scale_without_resampling /home/oceane/libsixel_asan/src/scale.c:214
    #1 0x7fc5bebe78d9 in sixel_helper_scale_image /home/oceane/libsixel_asan/src/scale.c:348
    #2 0x7fc5bebe1db9 in sixel_frame_resize /home/oceane/libsixel_asan/src/frame.c:570
    #3 0x7fc5bec9e18d in sixel_encoder_do_resize /home/oceane/libsixel_asan/src/encoder.c:641
    #4 0x7fc5bec9fd94 in sixel_encoder_encode_frame /home/oceane/libsixel_asan/src/encoder.c:968
    #5 0x7fc5bec86f6a in load_with_builtin /home/oceane/libsixel_asan/src/loader.c:963
    #6 0x7fc5bec90e67 in sixel_helper_load_image_file /home/oceane/libsixel_asan/src/loader.c:1418
    #7 0x7fc5becadde1 in sixel_encoder_encode /home/oceane/libsixel_asan/src/encoder.c:1743
    #8 0x558352bf5dcb in main /home/oceane/libsixel_asan/converters/img2sixel.c:457
    #9 0x7fc5be795082 in __libc_start_main ../csu/libc-start.c:308
    #10 0x558352bf67dd in _start (/home/oceane/libsixel_asan/build_asan/bin/img2sixel+0x67dd)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV /home/oceane/libsixel_asan/src/scale.c:214 in scale_without_resampling
==2489639==ABORTING

Case 2

Normal build

$ /home/oceane/libsixel_norm/libsixel/build/bin/img2sixel -w 40% -h 300% -r nearest poc_min2
Segmentation fault

with ASan

$ /home/oceane/libsixel_asan/build_asan/bin/img2sixel -w 40% -h 300% -r nearest poc_min2
=================================================================
==2012689==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x7f0b6a674610 at pc 0x7f0b702d6e05 bp 0x7ffdf2689970 sp 0x7ffdf2689960
READ of size 1 at 0x7f0b6a674610 thread T0
    #0 0x7f0b702d6e04 in scale_without_resampling /home/oceane/libsixel_asan/src/scale.c:214
    #1 0x7f0b702d6e04 in sixel_helper_scale_image /home/oceane/libsixel_asan/src/scale.c:348
    #2 0x7f0b702c5db9 in sixel_frame_resize /home/oceane/libsixel_asan/src/frame.c:570
    #3 0x7f0b7038218d in sixel_encoder_do_resize /home/oceane/libsixel_asan/src/encoder.c:641
    #4 0x7f0b70383d94 in sixel_encoder_encode_frame /home/oceane/libsixel_asan/src/encoder.c:968
    #5 0x7f0b7036af6a in load_with_builtin /home/oceane/libsixel_asan/src/loader.c:963
    #6 0x7f0b70374e67 in sixel_helper_load_image_file /home/oceane/libsixel_asan/src/loader.c:1418
    #7 0x7f0b70391de1 in sixel_encoder_encode /home/oceane/libsixel_asan/src/encoder.c:1743
    #8 0x55df72adadcb in main /home/oceane/libsixel_asan/converters/img2sixel.c:457
    #9 0x7f0b6fe79082 in __libc_start_main ../csu/libc-start.c:308
    #10 0x55df72adb7dd in _start (/home/oceane/libsixel_asan/build_asan/bin/img2sixel+0x67dd)

0x7f0b6a674610 is located 0 bytes to the right of 10952208-byte region [0x7f0b69c02800,0x7f0b6a674610)
allocated by thread T0 here:
    #0 0x7f0b70505808 in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cc:144
    #1 0x7f0b702c5bdc in sixel_frame_resize /home/oceane/libsixel_asan/src/frame.c:562

SUMMARY: AddressSanitizer: heap-buffer-overflow /home/oceane/libsixel_asan/src/scale.c:214 in scale_without_resampling
Shadow bytes around the buggy address:
  0x0fe1ed4c6870: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0fe1ed4c6880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0fe1ed4c6890: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0fe1ed4c68a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0fe1ed4c68b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0fe1ed4c68c0: 00 00[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0fe1ed4c68d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0fe1ed4c68e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0fe1ed4c68f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0fe1ed4c6900: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0fe1ed4c6910: 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
==2012689==ABORTING

pocs.zip

Environment

git commit 6a5be8b
Ubuntu 20.04.6 LTS
13th Gen Intel(R) Core(TM) i9-13900