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Code Issues Releases Activity

pngdec: check if previous frame exists instead of trusting sequence_number

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This fixes a segmentation fault caused by calling memcpy with NULL as
second argument in handle_p_frame_apng.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
This commit is contained in:
Andreas Cadhalpun 2016-11-25 22:09:51 +01:00
parent 55997d5043
commit 801b5c18c7
1 changed files with 2 additions and 1 deletions
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3
libavcodec/pngdec.c
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@ -922,7 +922,8 @@ static int decode_fctl_chunk(AVCodecContext *avctx, PNGDecContext *s,
return AVERROR_INVALIDDATA;
}
if (sequence_number == 0 && dispose_op == APNG_DISPOSE_OP_PREVIOUS) {
if ((sequence_number == 0 || !s->previous_picture.f->data[0]) &&
dispose_op == APNG_DISPOSE_OP_PREVIOUS) {
// No previous frame to revert to for the first frame
// Spec says to just treat it as a APNG_DISPOSE_OP_BACKGROUND
dispose_op = APNG_DISPOSE_OP_BACKGROUND;