dvdsubdec: validate offset2 similar to offset1

If it is negative, it causes segmentation faults in decode_rle.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
(cherry picked from commit f621749d1181987b3f815c6766ea66d6c5d55198)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/libavcodec/dvdsubdec.c b/libavcodec/dvdsubdec.c
index 7120f10a53..f009824401 100644
--- a/libavcodec/dvdsubdec.c
+++ b/libavcodec/dvdsubdec.c
@@ -346,7 +346,7 @@ static int decode_dvd_subtitles(DVDSubContext *ctx, AVSubtitle *sub_header,
             }
         }
     the_end:
-        if (offset1 >= 0) {
+        if (offset1 >= 0 && offset2 >= 0) {
             int w, h;
             uint8_t *bitmap;