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 <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2020-10-16 19:05:23 +02:00
parent 86228ebdb2
commit 3300f5c133

View File

@ -156,12 +156,14 @@ 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_EOF;
st = s->streams[0];
image = &ico->images[ico->current_image];
if ((ret = avio_seek(pb, image->offset, SEEK_SET)) < 0)