[FFmpeg-cvslog] lavf: fix signed overflow in avformat_find_stream_info()

[Mans Rullgard]

ffmpeg | branch: release/0.8 | Mans Rullgard <mans at mansr.com> | Sat Oct  8 02:06:26 2011 +0100| [edc942202b577946c265fe9fdff236fac2b2cc2f] | committer: Michael Niedermayer

lavf: fix signed overflow in avformat_find_stream_info()

On the first iteration through this code, last_dts is always
INT64_MIN (AV_NOPTS_VALUE) and the subtraction overflows in
an invalid manner.  Although the result is only used if the
input values are valid, performing the subtraction is still
not allowed in a strict environment.

Signed-off-by: Mans Rullgard <mans at mansr.com>
(cherry picked from commit a31e9f68a426f634e002282885c6c2eb1bfbea44)

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

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=edc942202b577946c265fe9fdff236fac2b2cc2f
---

 libavformat/utils.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavformat/utils.c b/libavformat/utils.c
index b15582a..400d968 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -2396,9 +2396,9 @@ int av_find_stream_info(AVFormatContext *ic)
         }
         {
             int64_t last = st->info->last_dts;
-            int64_t duration= pkt->dts - last;
 
-            if(pkt->dts != AV_NOPTS_VALUE && last != AV_NOPTS_VALUE && duration>0){
+            if(pkt->dts != AV_NOPTS_VALUE && last != AV_NOPTS_VALUE && pkt->dts > last){
+                int64_t duration= pkt->dts - last;
                 double dur= duration * av_q2d(st->time_base);
 
 //                if(st->codec->codec_type == AVMEDIA_TYPE_VIDEO)