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avcodec/mpeg12dec: Don't adapt (last|next)_pic.linesize for field pics

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These values are not read anywhere. Furthermore, since commit
fe6037fd04 the linesize values
of the MPVWorkPictures were wrong for subsequent fields
in a chain of B-pictures (as they are always doubled and no longer
based upon the frame-linesizes) which can eventually lead to overflow.

Finally, it makes no real sense to ever double the linesize
of the reference pictures at all: Even when the current picture
is a field, it can still reference both fields of reference
pictures and therefore the linesize should allow to address
both fields (for the same reason, data is not offset for
reference pictures).

libavcodec/mpeg12dec.c:1304:41: runtime error: signed integer overflow: 4611686018427387904 * 2 cannot be represented in type 'long'

issue: 69732/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEGVIDEO_fuzzer-5123551179374592

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2024-06-24 01:38:17 +02:00
parent f26255962c
commit 5a30b45c0f
1 changed files with 0 additions and 2 deletions
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libavcodec/mpeg12dec.c
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@ -1278,8 +1278,6 @@ static int mpeg_field_start(Mpeg1Context *s1, const uint8_t *buf, int buf_size)
s->cur_pic.linesize[i]);
}
s->cur_pic.linesize[i] *= 2;
s->last_pic.linesize[i] *= 2;
s->next_pic.linesize[i] *= 2;
}
}