Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Comment (by Balling):

 >The issue is that it is at least 3x slower than the default color
 conversion.

 Default color conversion is so wrong, it is useless really.


 Happy to hear that with the API flag the bug is gone.
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Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Comment (by Jerome):

 Replying to [comment:5 Balling]:
 > What I mean is that the default color convertion is buggy, no one should
 use that. And it only affects yuv420p to bgr, not to rgb.

 Ok, I found the flag `SWS_ACCURATE_RND`. With it, the memory issue is
 gone. The issue is that it is at least 3x slower than the default color
 conversion.
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Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Comment (by Jerome):

 Replying to [comment:5 Balling]:
 > What I mean is that the default color convertion is buggy, no one should
 use that. And it only affects yuv420p to bgr, not to rgb.

 Thank you for your reply. For this bug, I'm using the function `sws_scale`
 directly. Do you mean that this function is buggy? If this is the case,
 can you point me to an alternative?
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Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Comment (by Balling):

 What I mean is that the default color convertion is buggy, no one suld use
 that. And it only affects yuv420p to bgr, not to rgb.
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Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Comment (by Jerome):

 Seems related to https://trac.ffmpeg.org/ticket/9791.
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Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Description changed by Jerome:

Old description:

> Summary of the bug:
> This bug occurs when using the sws_scale function to convert the color
> space of an image from yuv420 to bgr24 (it might occur for other color
> spaces, I haven't verified).
> It started happening with version 5.0 and is still happening with the
> latest master. It does not systematically happen, only for some image
> resolution. When writing the output image, sws_scale goes beyond the
> image buffer by 8 bytes. This memory violation often triggers a segfault.
>
> Valgrind output:
> ==1050090== Memcheck, a memory error detector
> ==1050090== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et
> al.
> ==1050090== Using Valgrind-3.21.0 and LibVEX; rerun with -h for copyright
> info
> ==1050090== Command: ./test_memcheck
> ==1050090==
> [swscaler @ 0x62cb680] deprecated pixel format used, make sure you did
> set range correctly
> Convert unscaled 3240
> ==1050090== Invalid write of size 8
> ==1050090==at 0x48EEAF6: ??? (libavutil/x86/x86inc.asm:1274)
> ==1050090==by 0x48ED6F2: yuv420_bgr24_ssse3 (yuv2rgb_template.c:193)
> ==1050090==by 0x48B5B5F: scale_internal (swscale.c:1042)
> ==1050090==by 0x48B6668: sws_scale (swscale.c:1214)
> ==1050090==by 0x109393: main (main_memcheck.cpp:40)
> ==1050090==  Address 0x69aac40 is 0 bytes after a block of size 6,220,800
> alloc'd
> ==1050090==at 0x4847203: operator new[](unsigned long) (in
> /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==1050090==by 0x10931A: main (main_memcheck.cpp:23)
> ==1050090==
> ==1050090== Invalid write of size 8
> ==1050090==at 0x48EEAFB: ??? (libavutil/x86/x86inc.asm:1274)
> ==1050090==by 0x48ED6F2: yuv420_bgr24_ssse3 (yuv2rgb_template.c:193)
> ==1050090==by 0x48B5B5F: scale_internal (swscale.c:1042)
> ==1050090==by 0x48B6668: sws_scale (swscale.c:1214)
> ==1050090==by 0x109393: main (main_memcheck.cpp:40)
> ==1050090==  Address 0x69aac48 is 8 bytes after a block of size 6,220,800
> alloc'd
> ==1050090==at 0x4847203: operator new[](unsigned long) (in
> /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==1050090==by 0x10931A: main (main_memcheck.cpp:23)
>

> How to reproduce:
> I'm attaching a small C++ program that illustrates how to reproduce the
> bug.

New description:

 **Summary of the bug:**
 This bug occurs when using the sws_scale function to convert the color
 space of an image from yuv420 to bgr24 (it might occur for other color
 spaces, I haven't verified).
 It started happening with version 5.0 and is still happening with the
 latest master. It does not systematically happen, only for some image
 resolution. When writing the output image, sws_scale goes beyond the image
 buffer by 8 bytes. This memory violation often triggers a segfault.

 **Valgrind output:**

 {{{
 ==1050090== Memcheck, a memory error detector
 ==1050090== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et
 al.
 ==1050090== Using Valgrind-3.21.0 and LibVEX; rerun with -h for copyright
 info
 ==1050090== Command: ./test_memcheck
 ==1050090==
 [swscaler @ 0x62cb680] deprecated pixel format used, make sure you did set
 range correctly
 Convert unscaled 3240
 ==1050090== Invalid write of size 8
 ==1050090==at 0x48EEAF6: ??? (libavutil/x86/x86inc.asm:1274)
 ==1050090==by 0x48ED6F2: yuv420_bgr24_ssse3 (yuv2rgb_template.c:193)
 ==1050090==by 0x48B5B5F: scale_internal (swscale.c:1042)
 ==1050090==by 0x48B6668: sws_scale (swscale.c:1214)
 ==1050090==by 0x109393: main (main_memcheck.cpp:40)
 ==1050090==  Address 0x69aac40 is 0 bytes after a block of size 6,220,800
 alloc'd
 ==1050090==at 0x4847203: operator new[](unsigned long) (in
 /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
 ==1050090==by 0x10931A: main (main_memcheck.cpp:23)
 ==1050090==
 ==1050090== Invalid write of size 8
 ==1050090==at 0x48EEAFB: ??? (libavutil/x86/x86inc.asm:1274)
 ==1050090==by 0x48ED6F2: yuv420_bgr24_ssse3 (yuv2rgb_template.c:193)
 ==1050090==by 0x48B5B5F: scale_internal (swscale.c:1042)
 ==1050090==by 0x48B6668: sws_scale (swscale.c:1214)
 ==1050090==by 0x109393: main (main_memcheck.cpp:40)
 ==1050090==  Address 0x69aac48 is 8 bytes after a block of size 6,220,800
 alloc'd
 ==1050090==at 0x4847203: 

Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Comment (by Jerome):

 Replying to [comment:1 Balling]:
 > See bug #979, you need to test with -vf scale=flags=accurate_rnd

 Thank you for the comment. I don't believe this is related, though. In my
 case, I don't use the `ffmpeg` binary, but instead the `libswscale` shared
 library. And the issue is not about the precision of the color conversion,
 but the fact that it runs over the output buffer by 8 bytes for some
 resolutions.
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Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Comment (by Balling):

 See bug #979, you need to test with -vf scale=flags=accurate_rnd
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Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Changes (by Jerome):

 * Attachment "main_memcheck.cpp" added.

 source file to get the valgrind output
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Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Changes (by Jerome):

 * Attachment "Makefile" added.

 makefile
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Re: [FFmpeg-trac] #10852(swscale:new): sws_scale overflows buffer for some resolutions using ssse3 instructions

[FFmpeg]

#10852: sws_scale overflows buffer for some resolutions using ssse3 instructions
+---
 Reporter:  Jerome  |Owner:  (none)
 Type:  defect  |   Status:  new
 Priority:  important   |Component:  swscale
  Version:  git-master  |   Resolution:
 Keywords:  memory  |   Blocked By:
 Blocking:  |  Reproduced by developer:  0
Analyzed by developer:  0   |
+---
Changes (by Jerome):

 * Attachment "main.cpp" added.

 source file to reproduce the bug
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