[FFmpeg-cvslog] avcodec/dvdsubdec: Sanity check len in decode_rle()

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Thu Sep 13 03:33:50 2018 +0200| [c2f02af6968498b482d12cc27d0c91891c444a0a] | committer: Michael Niedermayer

avcodec/dvdsubdec: Sanity check len in decode_rle()

Fixes: Timeout
Fixes: 9778/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DVDSUB_fuzzer-5186007132536832

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 e7b023e1db9fb13175929c02a02846d03510ec91)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c2f02af6968498b482d12cc27d0c91891c444a0a
---

 libavcodec/dvdsubdec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/dvdsubdec.c b/libavcodec/dvdsubdec.c
index d017e771fc..4bdffeb700 100644
--- a/libavcodec/dvdsubdec.c
+++ b/libavcodec/dvdsubdec.c
@@ -124,6 +124,8 @@ static int decode_rle(uint8_t *bitmap, int linesize, int w, int h,
             len = decode_run_8bit(&gb, &color);
         else
             len = decode_run_2bit(&gb, &color);
+        if (len != INT_MAX && len > w - x)
+            return AVERROR_INVALIDDATA;
         len = FFMIN(len, w - x);
         memset(d + x, color, len);
         x += len;