From 091fdce87e88c8622d8af89ffa6cbb0dc20c3816 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Fri, 26 Apr 2024 23:22:53 +0200 Subject: [PATCH] avcodec/pngdec: Check last AVFrame before deref Fixes: NULL pointer dereference Fixes: 68184/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APNG_fuzzer-4926478069334016 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavcodec/pngdec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c index f7751223b8..8934a95a7f 100644 --- a/libavcodec/pngdec.c +++ b/libavcodec/pngdec.c @@ -1218,7 +1218,7 @@ static int decode_fctl_chunk(AVCodecContext *avctx, PNGDecContext *s, return AVERROR_INVALIDDATA; } - if ((sequence_number == 0 || !s->last_picture.f->data[0]) && + if ((sequence_number == 0 || !s->last_picture.f) && 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