From b71283c68fc7a4c867cd49b1280298bb9f87e58e Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Fri, 16 Oct 2020 19:05:23 +0200 Subject: [PATCH] avformat/icodec: Change order of operations to avoid NULL dereference Fixes: SEGV on unknown address 0x000000000000 Fixes: 26379/clusterfuzz-testcase-minimized-ffmpeg_dem_ICO_fuzzer-5709011753893888 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Reviewed-by: Peter Ross Signed-off-by: Michael Niedermayer (cherry picked from commit 3300f5c133650ba25f94531d40ecc94c79b84457) Signed-off-by: Michael Niedermayer --- libavformat/icodec.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/libavformat/icodec.c b/libavformat/icodec.c index 040e454c55..c07238ec67 100644 --- a/libavformat/icodec.c +++ b/libavformat/icodec.c @@ -124,12 +124,14 @@ static int read_packet(AVFormatContext *s, AVPacket *pkt) IcoDemuxContext *ico = s->priv_data; IcoImage *image; AVIOContext *pb = s->pb; - AVStream *st = s->streams[0]; + AVStream *st; int ret; if (ico->current_image >= ico->nb_images) return AVERROR(EIO); + st = s->streams[0]; + image = &ico->images[ico->current_image]; if ((ret = avio_seek(pb, image->offset, SEEK_SET)) < 0)