[FFmpeg-cvslog] avcodec/dxv: Check op_offset in dxv_decompress_cocg()

[Michael Niedermayer]

ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Tue May 21 01:33:03 2019 +0200| [43afeaa08652543fd44f993001b2be01aca122a6] | committer: Michael Niedermayer

avcodec/dxv: Check op_offset in dxv_decompress_cocg()

Fixes: signed integer overflow: -2147483648 - 12 cannot be represented in type 'int'
Fixes: 14732/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DXV_fuzzer-5735273129836544

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 8e520843dd76a644c019134ac7b17eba9f1118b3)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=43afeaa08652543fd44f993001b2be01aca122a6
---

 libavcodec/dxv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavcodec/dxv.c b/libavcodec/dxv.c
index aef5ec19dd..7ae3315493 100644
--- a/libavcodec/dxv.c
+++ b/libavcodec/dxv.c
@@ -743,6 +743,9 @@ static int dxv_decompress_cocg(DXVContext *ctx, GetByteContext *gb,
     int skip0, skip1, oi0 = 0, oi1 = 0;
     int ret, state0 = 0, state1 = 0;
 
+    if (op_offset < 12)
+        return AVERROR_INVALIDDATA;
+
     dst = tex_data;
     bytestream2_skip(gb, op_offset - 12);
     if (op_size0 > max_op_size0)