11-patch_fix-constraint-time-overflow-32bit.patch

From: Pekka Helenius <fincer89@hotmail.com>
Date: Thu, 13 Aug 2020 21:55:20 +0300
Subject: Cast constraint median time value to unsigned long. Fixes overflow on 32-bit systems.


--- a/src/constraint.c	2020-08-03 23:43:48.584926017 +0300
+++ b/src/constraint.c	2020-08-13 21:54:44.579053808 +0300
@@ -941,7 +941,14 @@ constraint_update(void)
 	/* calculate median */
 	i = cnt / 2;
 	if (cnt % 2 == 0)
-		conf->constraint_median = (values[i - 1] + values[i]) / 2;
+
+		/*
+		 * Casting to unsigned long (ul) is required on 32-bit systems.
+		 * Otherwise, the summed value exceed the maximum 32-bit time_t value and overflows
+		 * before divide operation, resulting to a great negative value which again leads to
+		 * an invalid constraint_median value.
+		 */
+		conf->constraint_median = ( (unsigned long)(values[i - 1] + values[i]) ) / 2;
 	else
 		conf->constraint_median = values[i];