[FFmpeg-cvslog] lavf: fix arithmetic overflows in avformat_seek_file()

[Mans Rullgard]

ffmpeg | branch: master | Mans Rullgard <mans at mansr.com> | Fri Dec  7 13:53:56 2012 +0000| [91ac403b1316d59b4f43c4ea0f237e24cec2819a] | committer: Mans Rullgard

lavf: fix arithmetic overflows in avformat_seek_file()

The values compared here can be more than INT64_MAX apart.  Since the
difference is always positive, converting to uint64_t before subtracting
gives the correct result without overflows.

Signed-off-by: Mans Rullgard <mans at mansr.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=91ac403b1316d59b4f43c4ea0f237e24cec2819a
---

 libavformat/utils.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavformat/utils.c b/libavformat/utils.c
index 12b054d..cd46caf 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1762,7 +1762,7 @@ int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int
     //Fallback to old API if new is not implemented but old is
     //Note the old has somewat different sematics
     if(s->iformat->read_seek || 1)
-        return av_seek_frame(s, stream_index, ts, flags | (ts - min_ts > (uint64_t)(max_ts - ts) ? AVSEEK_FLAG_BACKWARD : 0));
+        return av_seek_frame(s, stream_index, ts, flags | ((uint64_t)ts - min_ts > (uint64_t)max_ts - ts ? AVSEEK_FLAG_BACKWARD : 0));
 
     // try some generic seek like seek_frame_generic() but with new ts semantics
 }