From b4e77dfca1c2970446f79277034d8e60c3fe3f4e Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Fri, 23 Apr 2021 19:33:58 +0200
Subject: [PATCH] avformat/bfi: check nframes

Fixes: signed integer overflow: -2147483648 - 1 cannot be represented in type 'int'
Fixes: 29102/clusterfuzz-testcase-minimized-ffmpeg_dem_BFI_fuzzer-6737028768202752

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

diff --git a/libavformat/bfi.c b/libavformat/bfi.c
index bff6f0154e..69000118fa 100644
--- a/libavformat/bfi.c
+++ b/libavformat/bfi.c
@@ -73,6 +73,8 @@ static int bfi_read_header(AVFormatContext * s)
         return AVERROR_INVALIDDATA;
 
     bfi->nframes           = avio_rl32(pb);
+    if (bfi->nframes < 0)
+        return AVERROR_INVALIDDATA;
     avio_rl32(pb);
     avio_rl32(pb);
     avio_rl32(pb);