[FFmpeg-cvslog] avcodec/hevc_sei: Fix integer overflows in decode_nal_sei_message()

[Michael Niedermayer]

ffmpeg | branch: release/3.4 | Michael Niedermayer <michael at niedermayer.cc> | Fri Dec 15 17:50:12 2017 +0100| [2e426fae43f3a543649a6b9bf3ed6c0ae6892ce5] | committer: Michael Niedermayer

avcodec/hevc_sei: Fix integer overflows in decode_nal_sei_message()

Fixes: signed integer overflow: 2147483520 + 255 cannot be represented in type 'int'
Fixes: 4554/clusterfuzz-testcase-minimized-4843714515042304

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 991ef6e5b9a6a9d95e274ff6bff52db1c82b3808)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2e426fae43f3a543649a6b9bf3ed6c0ae6892ce5
---

 libavcodec/hevc_sei.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libavcodec/hevc_sei.c b/libavcodec/hevc_sei.c
index d0f9966a29..4fae797251 100644
--- a/libavcodec/hevc_sei.c
+++ b/libavcodec/hevc_sei.c
@@ -324,11 +324,15 @@ static int decode_nal_sei_message(GetBitContext *gb, HEVCSEIContext *s,
     av_log(logctx, AV_LOG_DEBUG, "Decoding SEI\n");
 
     while (byte == 0xFF) {
+        if (get_bits_left(gb) < 16 || payload_type > INT_MAX - 255)
+            return AVERROR_INVALIDDATA;
         byte          = get_bits(gb, 8);
         payload_type += byte;
     }
     byte = 0xFF;
     while (byte == 0xFF) {
+        if (get_bits_left(gb) < 8 + 8LL*payload_size)
+            return AVERROR_INVALIDDATA;
         byte          = get_bits(gb, 8);
         payload_size += byte;
     }