[FFmpeg-cvslog] avcodec/flicvideo: Check frame_size before decrementing

[Michael Niedermayer]

ffmpeg | branch: release/3.1 | Michael Niedermayer <michael at niedermayer.cc> | Wed May 17 01:12:55 2017 +0200| [792f15c109cc7f64d19ed139f63dcb4b33329eba] | committer: Michael Niedermayer

avcodec/flicvideo: Check frame_size before decrementing

Fixes: runtime error: signed integer overflow: -2147483627 - 22 cannot be represented in type 'int'
Fixes: 1637/clusterfuzz-testcase-minimized-5376582493405184

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 355e27e24dc88d6ba8f27501a34925d9d937a399)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=792f15c109cc7f64d19ed139f63dcb4b33329eba
---

 libavcodec/flicvideo.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavcodec/flicvideo.c b/libavcodec/flicvideo.c
index c9c6c24e55..192d4fe8a7 100644
--- a/libavcodec/flicvideo.c
+++ b/libavcodec/flicvideo.c
@@ -202,6 +202,9 @@ static int flic_decode_frame_8BPP(AVCodecContext *avctx,
     num_chunks = bytestream2_get_le16(&g2);
     bytestream2_skip(&g2, 8);  /* skip padding */
 
+    if (frame_size < 16)
+        return AVERROR_INVALIDDATA;
+
     frame_size -= 16;
 
     /* iterate through the chunks */
@@ -522,6 +525,8 @@ static int flic_decode_frame_15_16BPP(AVCodecContext *avctx,
     if (frame_size > buf_size)
         frame_size = buf_size;
 
+    if (frame_size < 16)
+        return AVERROR_INVALIDDATA;
     frame_size -= 16;
 
     /* iterate through the chunks */