[FFmpeg-trac] #8274(undetermined:new): heap-buffer-overflow at libavfilter/vf_avgblur.c:172

FFmpeg trac at avcodec.org
Tue Oct 15 17:13:56 EEST 2019


#8274: heap-buffer-overflow at libavfilter/vf_avgblur.c:172
-------------------------------------+-------------------------------------
             Reporter:  Suhwan       |                     Type:  defect
               Status:  new          |                 Priority:  important
            Component:               |                  Version:  git-
  undetermined                       |  master
             Keywords:  asan         |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 There is a heap-buffer-overflow at libavfilter/vf_avgblur.c:172 in
 filter_vertically_8
 I compiled ffmpeg with "--toolchain=clang-asan" to check the memory
 corruption and attached log file.
 How to reproduce:
 {{{
 % ffmpeg_g -y -i $PoC -filter_complex avgblur -target dv50 -loglevel 99
 tmp.acm

 ffmpeg version N-95382-g62f4722582 Copyright (c) 2000-2019 the FFmpeg
 developers
 built with clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
 configuration: --cc=clang --cxx=clang++ --ld=clang --enable-debug
 --toolchain=clang-asan
 }}}

 Here's ASAN log

 {{{
 =================================================================
 ==6091==ERROR: AddressSanitizer: heap-buffer-overflow on address
 0x609000006c50 at pc 0x0000009a519a bp 0x7ffff1725c40 sp 0x7ffff1725c38
 READ of size 4 at 0x609000006c50 thread T1
     #0 0x9a5199 in filter_vertically_8
 ffmpeg/libavfilter/vf_avgblur.c:172:1
     #1 0x942909 in worker_func ffmpeg/libavfilter/pthread.c:50:15
     #2 0x86863a2 in run_jobs ffmpeg/libavutil/slicethread.c:61:9
     #3 0x8683d0d in thread_worker ffmpeg/libavutil/slicethread.c:85:13
     #4 0x4eb9de in __asan::AsanThread::ThreadStart(unsigned long,
 __sanitizer::atomic_uintptr_t*) (ffmpeg_asan+0x4eb9de)
     #5 0x7ffff668e6da in start_thread (/lib/x86_64-linux-
 gnu/libpthread.so.0+0x76da)
     #6 0x7ffff5d9388e in clone /build/glibc-
 OTsEL5/glibc-2.27/misc/../sysdeps/unix/sysv/linux/x86_64/clone.S:95

 0x609000006c50 is located 0 bytes to the right of 16-byte region
 [0x609000006c40,0x609000006c50)
 allocated by thread T0 here:
     #0 0x4de9e8 in posix_memalign (ffmpeg_asan+0x4de9e8)
     #1 0x8592f19 in av_malloc ffmpeg/libavutil/mem.c:87:9
     #2 0x8592f19 in av_malloc_array ffmpeg/libavutil/mem.c:188
     #3 0x9a0bf3 in config_input ffmpeg/libavfilter/vf_avgblur.c:188:17

 Thread T1 created by T0 here:
     #0 0x436f80 in pthread_create (ffmpeg_asan+0x436f80)
     #1 0x8682ef9 in avpriv_slicethread_create
 ffmpeg/libavutil/slicethread.c:147:19

 SUMMARY: AddressSanitizer: heap-buffer-overflow
 ffmpeg/libavfilter/vf_avgblur.c:172:1 in filter_vertically_8
 Shadow bytes around the buggy address:
   0x0c127fff8d30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
   0x0c127fff8d40: 00 fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
   0x0c127fff8d50: 00 00 00 fa fa fa fa fa fa fa fa fa fa fa fa fa
   0x0c127fff8d60: 00 fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
   0x0c127fff8d70: 00 00 00 fa fa fa fa fa fa fa fa fa fa fa fa fa
 =>0x0c127fff8d80: fa fa fa fa fa fa fa fa 00 00[fa]fa fa fa fa fa
   0x0c127fff8d90: fa fa fa fa fa fa fa fa fd fa fa fa fa fa fa fa
   0x0c127fff8da0: fa fa fa fa fa fa fa fa fd fa fa fa fa fa fa fa
   0x0c127fff8db0: fa fa fa fa fa fa fa fa fd fa fa fa fa fa fa fa
   0x0c127fff8dc0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
   0x0c127fff8dd0: 00 00 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
 ==6091==ABORTING

 }}}
 Please confirm.
 Thanks

--
Ticket URL: <https://trac.ffmpeg.org/ticket/8274>
FFmpeg <https://ffmpeg.org>
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