[FFmpeg-cvslog] avcodec/dvdsubdec: error on bitmaps with size 0

[wm4]

ffmpeg | branch: release/2.4 | wm4 <nfxjfg at googlemail.com> | Wed Jan  7 23:57:50 2015 +0100| [2ba1af5791fc405ad648851344fe6dd83d1c92c1] | committer: Michael Niedermayer

avcodec/dvdsubdec: error on bitmaps with size 0

Attemtping to decode them could lead to invalid writes with some fuzzed
samples.

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
(cherry picked from commit bcaa9099b3648b47060e1724a97dc98b63c83702)

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2ba1af5791fc405ad648851344fe6dd83d1c92c1
---

 libavcodec/dvdsubdec.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavcodec/dvdsubdec.c b/libavcodec/dvdsubdec.c
index 5e22556..28027c2 100644
--- a/libavcodec/dvdsubdec.c
+++ b/libavcodec/dvdsubdec.c
@@ -108,6 +108,9 @@ static int decode_rle(uint8_t *bitmap, int linesize, int w, int h,
     if (start >= buf_size)
         return -1;
 
+    if (w <= 0 || h <= 0)
+        return -1;
+
     bit_len = (buf_size - start) * 8;
     init_get_bits(&gb, buf + start, bit_len);