avcodec/dvdsubdec: discard accumulated buffer on error

Fixes: Timeout
Fixes: 10992/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DVDSUB_fuzzer-5657495410835456
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/dvdsubdec.c b/libavcodec/dvdsubdec.c
index 632a53adabcb86b1841f94d2fecc1b2fb05d6f58..741ea9fd1e7377d946e1c4464681e9836a0fe4a9 100644 (file)
--- a/libavcodec/dvdsubdec.c
+++ b/libavcodec/dvdsubdec.c
@@ -595,6 +595,7 @@ static int dvdsub_decode(AVCodecContext *avctx,
     }
 
     if (is_menu < 0) {
+        ctx->buf_size = 0;
     no_subtitle:
         reset_rects(sub);
         *data_size = 0;