Bluetooth: Fix missing NULL check for smp_chan_create() return value

The smp_chan_create function may return NULL, e.g. in the case of memory
allocation failure, so we always need to check for this.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/smp.c

@@ -888,6 +888,8 @@ static u8 smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb)
 		return 0;
 
 	smp = smp_chan_create(conn);
+	if (!smp)
+		return SMP_UNSPECIFIED;
 
 	skb_pull(skb, sizeof(*rp));