#6763: swscale: Out-of-bounds memory accesses
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Reporter: Gramner | Owner: (none)
Type: defect | Status: new
Priority: important | Component: swscale
Version: git-master | Resolution:
Keywords: crash | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by hackerfactor):
I just ran into this same problem.
`sws_scale(swsctx, FrameIn->data,FrameIn->linesize, 0, FrameIn->height,
FrameOut->data, FrameOut->linesize);`
I included some debugging print lines:
```
Frame In: 540x360 linesize=640
Frame Out: 540x360 linesize=1620
```
The video is mp4, YUV444 and being converted to RGB24. It reports to
stderr:
`[swscaler @ 0x16c7300] Warning: data is not aligned! This can lead to a
speed loss`
The output buffer is allocated as 540x360x3 = 583200 bytes.
However, the misalignment causes sws_scale to write-overflow. (Valgrind
detected it.) I see the same problem when using vlc and other video
players on the same video since they use the same ffmpeg library.
My workaround: Allocate enough space to round up to a width that is
divisible by 8. (Allocate 544x360x3 = 587520 bytes.)
--
Ticket URL: <https://trac.ffmpeg.org/ticket/6763#comment:6>
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