[FFmpeg-cvslog] avformat/sauce: Check avio_size() for failure

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Thu Jul 11 20:49:08 2024 +0200| [477d964e32350c7a31abe05582ca4ceb6aba49fd] | committer: Michael Niedermayer

avformat/sauce: Check avio_size() for failure

Fixes: CID1604592 Overflowed constant

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 759aae590c0298414db4d2925a33b084d7f9e7f9)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=477d964e32350c7a31abe05582ca4ceb6aba49fd
---

 libavformat/sauce.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libavformat/sauce.c b/libavformat/sauce.c
index a2347b0197..424608f342 100644
--- a/libavformat/sauce.c
+++ b/libavformat/sauce.c
@@ -34,7 +34,12 @@ int ff_sauce_read(AVFormatContext *avctx, uint64_t *fsize, int *got_width, int g
     AVIOContext *pb = avctx->pb;
     char buf[36];
     int datatype, filetype, t1, t2, nb_comments;
-    uint64_t start_pos = avio_size(pb) - 128;
+    int64_t start_pos = avio_size(pb);
+
+    if (start_pos < 128)
+        return AVERROR_INVALIDDATA;
+
+    start_pos -= 128;
 
     avio_seek(pb, start_pos, SEEK_SET);
     if (avio_read(pb, buf, 7) != 7)