[FFmpeg-devel] [PATCH 2/4] avformat/gxf: Check pkt_len

[Michael Niedermayer]

Fixes: Infinite loop
Fixes: 26576/clusterfuzz-testcase-minimized-ffmpeg_dem_GXF_fuzzer-4823080360476672

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
---
 libavformat/gxf.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/libavformat/gxf.c b/libavformat/gxf.c
index 49364b7205..bbad47c240 100644
--- a/libavformat/gxf.c
+++ b/libavformat/gxf.c
@@ -285,9 +285,12 @@ static void gxf_track_tags(AVIOContext *pb, int *len, struct gxf_stream_info *si
 static void gxf_read_index(AVFormatContext *s, int pkt_len) {
     AVIOContext *pb = s->pb;
     AVStream *st;
-    uint32_t fields_per_map = avio_rl32(pb);
-    uint32_t map_cnt = avio_rl32(pb);
+    uint32_t fields_per_map, map_cnt;
     int i;
+    if (pkt_len < 8)
+        return;
+    fields_per_map = avio_rl32(pb);
+    map_cnt = avio_rl32(pb);
     pkt_len -= 8;
     if ((s->flags & AVFMT_FLAG_IGNIDX) || !s->streams) {
         avio_skip(pb, pkt_len);
-- 
2.17.1