Bluetooth: Fix bug when retransmitting I-frames

If there is no frames to retransmit l2cap was crashing the kernel, now
we check if the queue is empty first.

Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 8 insertions, 4 deletions

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index f9e4da2677af..4c7b2d22faa5 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -3546,7 +3546,8 @@ expected:
                 if (pi->conn_state & L2CAP_CONN_REJ_ACT)
                         pi->conn_state &= ~L2CAP_CONN_REJ_ACT;
                 else {
-                        sk->sk_send_head = TX_QUEUE(sk)->next;
+                        if (!skb_queue_empty(TX_QUEUE(sk)))
+                                sk->sk_send_head = TX_QUEUE(sk)->next;
                         pi->next_tx_seq = pi->expected_ack_seq;
                         l2cap_ertm_send(sk);
                 }
@@ -3593,7 +3594,8 @@ static inline void l2cap_data_channel_rrframe(struct sock *sk, u16 rx_control)
                 if (pi->conn_state & L2CAP_CONN_REJ_ACT)
                         pi->conn_state &= ~L2CAP_CONN_REJ_ACT;
                 else {
-                        sk->sk_send_head = TX_QUEUE(sk)->next;
+                        if (!skb_queue_empty(TX_QUEUE(sk)))
+                                sk->sk_send_head = TX_QUEUE(sk)->next;
                         pi->next_tx_seq = pi->expected_ack_seq;
                         l2cap_ertm_send(sk);
                 }
@@ -3625,12 +3627,14 @@ static inline void l2cap_data_channel_rejframe(struct sock *sk, u16 rx_control)
                 if (pi->conn_state & L2CAP_CONN_REJ_ACT)
                         pi->conn_state &= ~L2CAP_CONN_REJ_ACT;
                 else {
-                        sk->sk_send_head = TX_QUEUE(sk)->next;
+                        if (!skb_queue_empty(TX_QUEUE(sk)))
+                                sk->sk_send_head = TX_QUEUE(sk)->next;
                         pi->next_tx_seq = pi->expected_ack_seq;
                         l2cap_ertm_send(sk);
                 }
         } else {
-                sk->sk_send_head = TX_QUEUE(sk)->next;
+                if (!skb_queue_empty(TX_QUEUE(sk)))
+                        sk->sk_send_head = TX_QUEUE(sk)->next;
                 pi->next_tx_seq = pi->expected_ack_seq;
                 l2cap_ertm_send(sk);