From 344ef36b5a4f84ee536324a5e1db5b2b388de228 Mon Sep 17 00:00:00 2001
From: Edward Hervey <edward@centricular.com>
Date: Fri, 3 Jan 2025 11:59:43 +0100
Subject: [PATCH] videorate: Avoid overflow in calculations

base_ts and next_end_ts are both guint64. Use explicit check to avoid "negative"
timestamps (which would overflow, not be negative).

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8286>
---
 subprojects/gst-plugins-base/gst/videorate/gstvideorate.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/subprojects/gst-plugins-base/gst/videorate/gstvideorate.c b/subprojects/gst-plugins-base/gst/videorate/gstvideorate.c
index 655e299cd1..6a4a591dbb 100644
--- a/subprojects/gst-plugins-base/gst/videorate/gstvideorate.c
+++ b/subprojects/gst-plugins-base/gst/videorate/gstvideorate.c
@@ -1921,8 +1921,12 @@ gst_video_rate_transform_ip (GstBaseTransform * trans, GstBuffer * buffer)
 
         next_ts = videorate->base_ts - (
             (videorate->base_ts - next_ts) * videorate->rate);
-        next_end_ts = videorate->base_ts - (MAX (0,
-                (videorate->base_ts - next_end_ts)) * videorate->rate);
+        if (videorate->base_ts > next_end_ts)
+          next_end_ts =
+              videorate->base_ts - ((videorate->base_ts -
+                  next_end_ts) * videorate->rate);
+        else
+          next_end_ts = videorate->base_ts;
 
         diff1 = ABSDIFF (prev_endtime, next_end_ts);
         diff2 = ABSDIFF (in_endtime, next_end_ts);