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Date: Thu, 17 Aug 2017 20:19:01 +0000
From: "Agostino Sarubbo" <ago@...too.org>
To: "oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>
Subject: libfpx: heap-based buffer overflow in OLEStream::WriteVT_LPSTR (olestrm.cpp)

Description:
libfpx is a library for manipulating FlashPIX images.

I’m aware that the link to the upstream website does not work. I’m keeping it as well because in the future the upstream website could appear 
again.
Libfpx is not actively developed, I contacted the imagemagick project if they were available to patch security issues, but they said the they 
are only accepting patches and push new releases.
This issue was found using the gm command line tool of graphicsmagick.

The complete ASan output of the issue:

# gm identify $FILE
==11148==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000001cd1 at pc 0x00000043ebe2 bp 0x7ffc6fa94b20 sp 0x7ffc6fa942d0
READ of size 2 at 0x602000001cd1 thread T0
    #0 0x43ebe1 in __interceptor_strlen /var/tmp/portage/sys-libs/compiler-rt-sanitizers-4.0.1/work/compiler-rt-4.0.1.src/lib/asan/../sanitizer_common/sanitizer_common_interceptors.inc:284
    #1 0x7fd59be76493 in OLEStream::WriteVT_LPSTR(char*) /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/ole/olestrm.cpp:1472
    #2 0x7fd59be72e06 in OLEPropertySection::Write() /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/ole/oleprops.cpp:477
    #3 0x7fd59be73101 in OLEPropertySet::Commit() /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/ole/oleprops.cpp:131
    #4 0x7fd59be4da36 in PFlashPixFile::Commit() /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/fpx/fpxformt.cpp:581
    #5 0x7fd59be4da8f in PFlashPixFile::~PFlashPixFile() /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/fpx/fpxformt.cpp:276
    #6 0x7fd59be4db78 in PFlashPixFile::~PFlashPixFile() /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/fpx/fpxformt.cpp:306
    #7 0x7fd59be79ed3 in PHierarchicalImage::~PHierarchicalImage() /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/ri_image/ph_image.cpp:168
    #8 0x7fd59be49c38 in PFileFlashPixIO::~PFileFlashPixIO() /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/fpx/f_fpxio.cpp:277
    #9 0x7fd59be536a5 in PFlashPixImageView::~PFlashPixImageView() /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/fpx/fpximgvw.cpp:519
    #10 0x7fd59be536b8 in PFlashPixImageView::~PFlashPixImageView() /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/fpx/fpximgvw.cpp:532
    #11 0x7fd59be5529e in FPX_CloseImage /var/tmp/portage/media-libs/libfpx-1.3.1_p6/work/libfpx-1.3.1-6/fpx/fpxlibio.cpp:766
    #12 0x7fd59c0c7bf4 in ReadFPXImage /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/coders/fpx.c:344:14
    #13 0x7fd5a193ee2b in ReadImage /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/constitute.c:1607:13
    #14 0x7fd5a193be8c in PingImage /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/constitute.c:1370:9
    #15 0x7fd5a1807ae5 in IdentifyImageCommand /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:8379:17
    #16 0x7fd5a180e065 in MagickCommand /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:8869:17
    #17 0x7fd5a18b97fb in GMCommandSingle /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:17396:10
    #18 0x7fd5a18b6931 in GMCommand /var/tmp/portage/media-gfx/graphicsmagick-1.3.26/work/GraphicsMagick-1.3.26/magick/command.c:17449:16
    #19 0x7fd5a0121680 in __libc_start_main /var/tmp/portage/sys-libs/glibc-2.23-r4/work/glibc-2.23/csu/../csu/libc-start.c:289
    #20 0x419cd8 in _init (/usr/bin/gm+0x419cd8)

0x602000001cd1 is located 0 bytes to the right of 1-byte region [0x602000001cd0,0x602000001cd1)
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 0x7fd59bac5337 in operator new(unsigned long) (/usr/lib/gcc/x86_64-pc-linux-gnu/6.4.0/libstdc++.so.6+0xb2337)

SUMMARY: AddressSanitizer: heap-buffer-overflow /var/tmp/portage/sys-libs/compiler-rt-sanitizers-4.0.1/work/compiler-rt-4.0.1.src/lib/asan/../sanitizer_common/sanitizer_common_interceptors.inc:284 in __interceptor_strlen
Shadow bytes around the buggy address:
  0x0c047fff8340: fa fa 01 fa fa fa 00 06 fa fa fd fa fa fa fd fa
  0x0c047fff8350: fa fa fd fa fa fa 00 fa fa fa 00 05 fa fa fd fa
  0x0c047fff8360: fa fa fd fa fa fa 00 00 fa fa 04 fa fa fa fd fd
  0x0c047fff8370: fa fa fd fa fa fa fd fa fa fa fd fd fa fa fd fa
  0x0c047fff8380: fa fa fd fa fa fa fd fd fa fa 01 fa fa fa 00 00
=>0x0c047fff8390: fa fa fd fa fa fa fd fa fa fa[01]fa fa fa fd fd
  0x0c047fff83a0: fa fa 00 00 fa fa 00 04 fa fa fa fa fa fa fa fa
  0x0c047fff83b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff83c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff83d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c047fff83e0: 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
==11148==ABORTING

Affected version:
1.3.1_p6

Fixed version:
N/A

Commit fix:
N/A

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

CVE:
CVE-2017-12919

Reproducer:
https://github.com/asarubbo/poc/blob/master/00309-libfpx-heapoverflow-OLEStream_WriteVT_LPSTR

Timeline:
2017-08-01: bug discovered
2017-08-09: blog post about the issue
2017-08-17: 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/2017/08/09/libfpx-heap-based-buffer-overflow-in-olestreamwritevt_lpstr-olestrm-cpp/

--
Agostino Sarubbo
Gentoo Linux Developer


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