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avcodec/mobiclip: Check that Motion vectors are within the input frame

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The MV checks did not consider the width and height of the block, also they
had some off by 1 errors. This resulted in undefined behavior and crashes.
This commit instead errors out on these

Fixes: out of array read
Fixes: 26080/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MOBICLIP_fuzzer-5758146355920896

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2020-10-02 22:48:12 +02:00
parent b6b640c544
commit 92233a6344
1 changed files with 6 additions and 24 deletions
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30
libavcodec/mobiclip.c
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@ -1189,14 +1189,14 @@ static int predict_motion(AVCodecContext *avctx,
dst_linesize = s->pic[s->current_pic]->linesize[i];
dst = s->pic[s->current_pic]->data[i] + offsetx + offsety * dst_linesize;
if (offsetx + (mv.x >> 1) < 0 ||
offsety + (mv.y >> 1) < 0 ||
offsetx + width + (mv.x + 1 >> 1) > fwidth ||
offsety + height + (mv.y + 1 >> 1) > fheight)
return AVERROR_INVALIDDATA;
switch (method) {
case 0:
if (offsety + (mv.y >> 1) < 0 ||
offsety + (mv.y >> 1) >= fheight ||
offsetx + (mv.x >> 1) < 0 ||
offsetx + (mv.x >> 1) >= fwidth)
return AVERROR_INVALIDDATA;
src = s->pic[sidx]->data[i] + offsetx + (mv.x >> 1) +
(offsety + (mv.y >> 1)) * src_linesize;
for (int y = 0; y < height; y++) {
@ -1207,12 +1207,6 @@ static int predict_motion(AVCodecContext *avctx,
}
break;
case 1:
if (offsety + (mv.y >> 1) < 0 ||
offsety + (mv.y >> 1) >= fheight ||
offsetx + (mv.x >> 1) < 0 ||
offsetx + (mv.x >> 1) >= fwidth)
return AVERROR_INVALIDDATA;
src = s->pic[sidx]->data[i] + offsetx + (mv.x >> 1) +
(offsety + (mv.y >> 1)) * src_linesize;
for (int y = 0; y < height; y++) {
@ -1225,12 +1219,6 @@ static int predict_motion(AVCodecContext *avctx,
}
break;
case 2:
if (offsety + (mv.y >> 1) < 0 ||
offsety + (mv.y >> 1) >= fheight - 1 ||
offsetx + (mv.x >> 1) < 0 ||
offsetx + (mv.x >> 1) >= fwidth)
return AVERROR_INVALIDDATA;
src = s->pic[sidx]->data[i] + offsetx + (mv.x >> 1) +
(offsety + (mv.y >> 1)) * src_linesize;
for (int y = 0; y < height; y++) {
@ -1243,12 +1231,6 @@ static int predict_motion(AVCodecContext *avctx,
}
break;
case 3:
if (offsety + (mv.y >> 1) < 0 ||
offsety + (mv.y >> 1) >= fheight - 1 ||
offsetx + (mv.x >> 1) < 0 ||
offsetx + (mv.x >> 1) >= fwidth)
return AVERROR_INVALIDDATA;
src = s->pic[sidx]->data[i] + offsetx + (mv.x >> 1) +
(offsety + (mv.y >> 1)) * src_linesize;
for (int y = 0; y < height; y++) {