[FFmpeg-cvslog] avcodec/microdvddec: limit style characters in parsing

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sat Aug  4 02:56:56 2018 +0200| [f91e7ec9dfb32dd27c2474de4f98a2e47126f7a7] | committer: Michael Niedermayer

avcodec/microdvddec: limit style characters in parsing

Fixes: Timeout
Fixes: 9293/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MICRODVD_fuzzer-5643972541153280

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f91e7ec9dfb32dd27c2474de4f98a2e47126f7a7
---

 libavcodec/microdvddec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/microdvddec.c b/libavcodec/microdvddec.c
index 4a34267793..dad0ec8a22 100644
--- a/libavcodec/microdvddec.c
+++ b/libavcodec/microdvddec.c
@@ -99,7 +99,7 @@ static char *microdvd_load_tags(struct microdvd_tag *tags, char *s)
         case 'Y':
             tag.persistent = MICRODVD_PERSISTENT_ON;
         case 'y':
-            while (*s && *s != '}') {
+            while (*s && *s != '}' && s - start < 256) {
                 int style_index = indexof(MICRODVD_STYLES, *s);
 
                 if (style_index >= 0)