[BlueZ v2 02/20] attrib/gatt: Guard against possible integer overflow

[Bastien Nocera <hadess@hadess.net>]

Error: INTEGER_OVERFLOW (CWE-190): [#def30]
bluez-5.75/attrib/gatt.c:1016:2: known_value_assign: "last" = "65535", its value is now 65535.
bluez-5.75/attrib/gatt.c:1087:2: overflow_const: Expression "dd->start", which is equal to 65536, where "last + 1" is known to be equal to 65536, overflows the type that receives it, an unsigned integer 16 bits wide.
1085|		}
1086|
1087|->		dd->start = last + 1;
1088|
1089|		if (last < dd->end && !uuid_found) {
---
 attrib/gatt.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/attrib/gatt.c b/attrib/gatt.c
index b496dd1ebd95..3cedae9d167a 100644
--- a/attrib/gatt.c
+++ b/attrib/gatt.c
@@ -1076,10 +1076,12 @@ static void desc_discovered_cb(guint8 status, const guint8 *ipdu,
 	att_data_list_free(list);
 
 	/*
-	 * If last handle is lower from previous start handle then it is smth
-	 * wrong. Let's stop search, otherwise we might enter infinite loop.
+	 * If last handle is lower from previous start handle or if iterating
+	 * to the next handle from the last possible offset would overflow, then
+	 * something is wrong. Let's stop search, otherwise we might enter
+	 * infinite loop.
 	 */
-	if (last < dd->start) {
+	if (last < dd->start || last == G_MAXUINT16) {
 		err = ATT_ECODE_UNLIKELY;
 		goto done;
 	}
-- 
2.44.0