[FFmpeg-cvslog] avfilter/src_movie: fix how we check for overflows with seek_point
Marios Titas
git at videolan.org
Thu Apr 28 05:29:20 CEST 2016
ffmpeg | branch: release/2.7 | Marios Titas <redneb at gmx.com> | Sat Apr 2 21:11:44 2016 +0300| [3d9f1c0dbbcba0164ec5f0bd3497c481afc43062] | committer: Michael Niedermayer
avfilter/src_movie: fix how we check for overflows with seek_point
Currently, if the movie source filter is used and a seek_point is
specified on a file that has a negative start time, ffmpeg will fail.
An easy way to reproduce this is as follows:
$ ffmpeg -vsync passthrough -filter_complex 'color=d=10,setpts=PTS-1/TB' test.mp4
$ ffmpeg -filter_complex 'movie=filename=test.mp4:seek_point=2' -f null -
The problem is caused by checking for int64_t overflow the wrong way.
In general, to check whether a + b overflows, it is not enough to do:
a > INT64_MAX - b
because b might be negative; the correct way is:
b > 0 && > a > INT64_MAX - b
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit c1f9734f977f59bc0034096afbe8e43e40d93a5d)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=3d9f1c0dbbcba0164ec5f0bd3497c481afc43062
---
libavfilter/src_movie.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libavfilter/src_movie.c b/libavfilter/src_movie.c
index 908c03e..6df52f7 100644
--- a/libavfilter/src_movie.c
+++ b/libavfilter/src_movie.c
@@ -240,7 +240,7 @@ static av_cold int movie_common_init(AVFilterContext *ctx)
timestamp = movie->seek_point;
// add the stream start time, should it exist
if (movie->format_ctx->start_time != AV_NOPTS_VALUE) {
- if (timestamp > INT64_MAX - movie->format_ctx->start_time) {
+ if (timestamp > 0 && movie->format_ctx->start_time > INT64_MAX - timestamp) {
av_log(ctx, AV_LOG_ERROR,
"%s: seek value overflow with start_time:%"PRId64" seek_point:%"PRId64"\n",
movie->file_name, movie->format_ctx->start_time, movie->seek_point);
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