[core,gcc] add monitor rect sanity checks

Author: akallabeth

libfreerdp/core/gcc.c

@@ -2145,10 +2145,19 @@ BOOL gcc_read_client_monitor_data(wStream* s, rdpMcs* mcs)
 		const INT32 right = Stream_Get_INT32(s);   /* right */
 		const INT32 bottom = Stream_Get_INT32(s);  /* bottom */
 		const UINT32 flags = Stream_Get_UINT32(s); /* flags */
+
+		if ((left > right) || (bottom > top))
+			return FALSE;
+
+		const INT32 w = right - left;
+		const INT32 h = bottom - top;
+		if ((w >= INT32_MAX) || (h >= INT32_MAX))
+			return FALSE;
+
 		current->x = left;
 		current->y = top;
-		current->width = right - left + 1;
-		current->height = bottom - top + 1;
+		current->width = w + 1;
+		current->height = h + 1;
 		current->is_primary = (flags & MONITOR_PRIMARY) ? TRUE : FALSE;
 	}