avformat/bfi: Check chunk_header

Fixes: signed integer overflow: -2147483648 - 3 cannot be represented in type 'int'
Fixes: 26910/clusterfuzz-testcase-minimized-ffmpeg_dem_BFI_fuzzer-6665764123836416
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavformat/bfi.c b/libavformat/bfi.c
index 29e2cf8cf4193d9151768b727dabdd108106d367..2dab986f3af75ecf4bc0ca4aab6cb492e616723c 100644 (file)
--- a/libavformat/bfi.c
+++ b/libavformat/bfi.c
@@ -69,6 +69,9 @@ static int bfi_read_header(AVFormatContext * s)
     /* Set the total number of frames. */
     avio_skip(pb, 8);
     chunk_header           = avio_rl32(pb);
+    if (chunk_header < 3)
+        return AVERROR_INVALIDDATA;
+
     bfi->nframes           = avio_rl32(pb);
     avio_rl32(pb);
     avio_rl32(pb);