avcodec/dxv: Check op_offset in both directions

Fixes: signed integer overflow: 61 + 2147483647 cannot be represented in type 'int'
Fixes: 15311/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DXV_fuzzer-5742552826773504
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/libavcodec/dxv.c b/libavcodec/dxv.c
index ae79de981f7d9441f7c7ff17ee8f41c34046d17d..8d5e4b1c6c5aede53638f7c5f5677f7c31297294 100644 (file)
--- a/libavcodec/dxv.c
+++ b/libavcodec/dxv.c
@@ -745,7 +745,7 @@ 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)
+    if (op_offset < 12 || op_offset - 12 > bytestream2_get_bytes_left(gb))
         return AVERROR_INVALIDDATA;
 
     dst = tex_data;