calendarspec: use ADD_SAFE for repeat offset calculation

Use overflow-safe ADD_SAFE() instead of raw addition when
computing the next matching calendar component with repeat.
On overflow, skip the component instead of using a bogus value.

CID#1548052

Follow-up for a2eb5ea79c53620cfcf616e83bfac0c431247f86

diff --git a/src/shared/calendarspec.c b/src/shared/calendarspec.c
index dc13ae0f77994f11a3ea09230d75362bca0c0020..df371ac4f8cc72ea8280935864905981ebe7caf2 100644 (file)
--- a/src/shared/calendarspec.c
+++ b/src/shared/calendarspec.c
@@ -1149,9 +1149,8 @@ static int find_matching_component(
                 } else if (c->repeat > 0) {
                         int k;
 
-                        k = start + ROUND_UP(*val - start, c->repeat);
-
-                        if ((!d_set || k < d) && (stop < 0 || k <= stop)) {
+                        if (ADD_SAFE(&k, start, ROUND_UP(*val - start, c->repeat)) &&
+                            (!d_set || k < d) && (stop < 0 || k <= stop)) {
                                 d = k;
                                 d_set = true;
                         }