[FFmpeg-cvslog] avcodec/get_bits: Fix get_sbits_long(0)
Michael Niedermayer
git at videolan.org
Tue Dec 6 01:27:33 EET 2016
ffmpeg | branch: release/3.2 | Michael Niedermayer <michael at niedermayer.cc> | Sat Dec 3 23:44:56 2016 +0100| [334901aea0e351005a9e3d9d7c96f8158224914b] | committer: Michael Niedermayer
avcodec/get_bits: Fix get_sbits_long(0)
Fixes undefined behavior
Fixes: 640889-media
Found-by: Matt Wolenetz <wolenetz at google.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit c72fa432349881d5a445cd110abf698cc94d490d)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=334901aea0e351005a9e3d9d7c96f8158224914b
---
libavcodec/get_bits.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/libavcodec/get_bits.h b/libavcodec/get_bits.h
index 0f183e0..e888841 100644
--- a/libavcodec/get_bits.h
+++ b/libavcodec/get_bits.h
@@ -369,6 +369,10 @@ static inline uint64_t get_bits64(GetBitContext *s, int n)
*/
static inline int get_sbits_long(GetBitContext *s, int n)
{
+ // sign_extend(x, 0) is undefined
+ if (!n)
+ return 0;
+
return sign_extend(get_bits_long(s, n), n);
}
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