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Date: Fri, 18 Aug 2017 13:55:24 +0000
From: "Agostino Sarubbo" <ago@...too.org>
To: "oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>
Subject: graphicsmagick: heap-based buffer overflow in ReadSUNImage (sun.c)

Description:
graphicsmagick is a collection of tools and libraries for many image formats.

The complete ASan output of the issue:

# gm convert -clip -negate $FILE out
==18510==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000015f4 at pc 0x7f6e936c556b bp 0x7fff17c33ab0 sp 0x7fff17c33aa8
READ of size 4 at 0x6020000015f4 thread T0
    #0 0x7f6e936c556a in ReadSUNImage /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/coders/sun.c:581:26
    #1 0x7f6e98fa8e88 in ReadImage /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/constitute.c:1607:13
    #2 0x7f6e98e3bf18 in ConvertImageCommand /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:4348:22
    #3 0x7f6e98e780c5 in MagickCommand /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:8869:17
    #4 0x7f6e98f2385b in GMCommandSingle /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:17396:10
    #5 0x7f6e98f20991 in GMCommand /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:17449:16
    #6 0x7f6e9778b680 in __libc_start_main /var/tmp/portage/sys-libs/glibc-2.23-r4/work/glibc-2.23/csu/../csu/libc-start.c:289
    #7 0x419cd8 in _init (/usr/bin/gm+0x419cd8)

0x6020000015f4 is located 0 bytes to the right of 4-byte region [0x6020000015f0,0x6020000015f4)
allocated by thread T0 here:
    #0 0x4cf688 in malloc /var/tmp/portage/sys-libs/compiler-rt-sanitizers-4.0.1/work/compiler-rt-4.0.1.src/lib/asan/asan_malloc_linux.cc:66
    #1 0x7f6e9938a4d6 in MagickMalloc /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/memory.c:156:10
    #2 0x7f6e98db2590 in AllocateImageColormap /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/colormap.c:76:21
    #3 0x7f6e936b0f87 in ReadSUNImage /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/coders/sun.c:428:14
    #4 0x7f6e98fa8e88 in ReadImage /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/constitute.c:1607:13
    #5 0x7f6e98e3bf18 in ConvertImageCommand /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:4348:22
    #6 0x7f6e98e780c5 in MagickCommand /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:8869:17
    #7 0x7f6e98f2385b in GMCommandSingle /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:17396:10
    #8 0x7f6e98f20991 in GMCommand /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:17449:16
    #9 0x7f6e9778b680 in __libc_start_main /var/tmp/portage/sys-libs/glibc-2.23-r4/work/glibc-2.23/csu/../csu/libc-start.c:289

SUMMARY: AddressSanitizer: heap-buffer-overflow /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/coders/sun.c:581:26 in ReadSUNImage
Shadow bytes around the buggy address:
  0x0c047fff8260: fa fa 04 fa fa fa 00 00 fa fa 00 00 fa fa fd fd
  0x0c047fff8270: fa fa fd fd fa fa 07 fa fa fa fd fd fa fa 00 01
  0x0c047fff8280: fa fa 00 00 fa fa fd fa fa fa fd fa fa fa 02 fa
  0x0c047fff8290: fa fa 02 fa fa fa 00 fa fa fa 06 fa fa fa 00 fa
  0x0c047fff82a0: fa fa 00 07 fa fa 04 fa fa fa 04 fa fa fa fd fa
=>0x0c047fff82b0: fa fa 00 00 fa fa 00 00 fa fa 04 fa fa fa[04]fa
  0x0c047fff82c0: fa fa fd fa fa fa 00 00 fa fa fa fa fa fa fa fa
  0x0c047fff82d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff82e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff82f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff8300: 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
==18510==ABORTING

Affected version:
1.3.26

Fixed version:
N/A

Commit fix:
http://hg.code.sf.net/p/graphicsmagick/code/rev/95d00d55e978

Credit:
This bug was discovered by Agostino Sarubbo of Gentoo.

CVE:
CVE-2017-12937

Reproducer:
https://github.com/asarubbo/poc/blob/master/00304-graphicsmagick-heapoverflow-ReadSUNImage

Timeline:
2017-07-17: bug discovered and reported to upstream
2017-07-31: upstream released a fix
2017-08-05: blog post about the issue
2017-08-18: CVE assigned

Note:
This bug was found with American Fuzzy Lop.
This bug was identified with bare metal servers donated by Packet. This work is also supported by the Core Infrastructure Initiative.

Permalink:
https://blogs.gentoo.org/ago/2017/08/05/graphicsmagick-heap-based-buffer-overflow-in-readsunimage-sun-c/

--
Agostino Sarubbo
Gentoo Linux Developer


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