avcodec/pdvdec: Check previous frame before using it

Fixes: load of null pointer of type 'uint8_t' (aka 'unsigned char')
Fixes: 58256/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PDV_fuzzer-4776436325285888

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2023-05-02 01:55:34 +02:00
parent ed3691338b
commit 5cc378cc46
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1 changed files with 1 additions and 1 deletions

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@ -93,7 +93,7 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
return AVERROR_INVALIDDATA;
}
if (!(avpkt->flags & AV_PKT_FLAG_KEY)) {
if (prev && !(avpkt->flags & AV_PKT_FLAG_KEY)) {
for (int j = 0; j < (avctx->width + 7) >> 3; j++)
dst[j] ^= prev[j];
prev += prev_frame->linesize[0];