Bluetooth: Fix race condition on l2cap_ertm_send()
l2cap_ertm_send() can be called both from user context and bottom half context. The socket locks for that contexts are different, the user context uses a mutex(which can sleep) and the second one uses a spinlock_bh. That creates a race condition when we have interruptions on both contexts at the same time. The better way to solve this is to add a new spinlock to lock l2cap_ertm_send() and the vars it access. The other solution was to defer l2cap_ertm_send() with a workqueue, but we the sending process already has one defer on the hci layer. It's not a good idea add another one. The patch refactor the code to create l2cap_retransmit_frames(), then we encapulate the lock of l2cap_ertm_send() for some call. It also changes l2cap_retransmit_frame() to l2cap_retransmit_one_frame() to avoid confusion 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>
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@ -353,6 +353,7 @@ struct l2cap_pinfo {
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__le16 sport;
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spinlock_t send_lock;
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struct timer_list retrans_timer;
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struct timer_list monitor_timer;
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struct timer_list ack_timer;
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@ -1368,7 +1368,7 @@ static int l2cap_streaming_send(struct sock *sk)
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return 0;
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}
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static void l2cap_retransmit_frame(struct sock *sk, u8 tx_seq)
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static void l2cap_retransmit_one_frame(struct sock *sk, u8 tx_seq)
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{
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struct l2cap_pinfo *pi = l2cap_pi(sk);
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struct sk_buff *skb, *tx_skb;
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@ -1467,10 +1467,29 @@ static int l2cap_ertm_send(struct sock *sk)
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return nsent;
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}
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static int l2cap_retransmit_frames(struct sock *sk)
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{
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struct l2cap_pinfo *pi = l2cap_pi(sk);
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int ret;
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spin_lock_bh(&pi->send_lock);
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if (!skb_queue_empty(TX_QUEUE(sk)))
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sk->sk_send_head = TX_QUEUE(sk)->next;
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pi->next_tx_seq = pi->expected_ack_seq;
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ret = l2cap_ertm_send(sk);
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spin_unlock_bh(&pi->send_lock);
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return ret;
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}
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static void l2cap_send_ack(struct l2cap_pinfo *pi)
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{
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struct sock *sk = (struct sock *)pi;
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u16 control = 0;
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int nframes;
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control |= pi->buffer_seq << L2CAP_CTRL_REQSEQ_SHIFT;
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@ -1479,10 +1498,17 @@ static void l2cap_send_ack(struct l2cap_pinfo *pi)
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pi->conn_state |= L2CAP_CONN_RNR_SENT;
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l2cap_send_sframe(pi, control);
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return;
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} else if (l2cap_ertm_send(sk) == 0) {
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}
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spin_lock_bh(&pi->send_lock);
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nframes = l2cap_ertm_send(sk);
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spin_unlock_bh(&pi->send_lock);
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if (nframes > 0)
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return;
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control |= L2CAP_SUPER_RCV_READY;
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l2cap_send_sframe(pi, control);
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}
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}
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static void l2cap_send_srejtail(struct sock *sk)
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@ -1673,8 +1699,10 @@ static inline int l2cap_sar_segment_sdu(struct sock *sk, struct msghdr *msg, siz
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size += buflen;
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}
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skb_queue_splice_tail(&sar_queue, TX_QUEUE(sk));
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spin_lock_bh(&pi->send_lock);
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if (sk->sk_send_head == NULL)
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sk->sk_send_head = sar_queue.next;
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spin_unlock_bh(&pi->send_lock);
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return size;
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}
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@ -1745,8 +1773,15 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms
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goto done;
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}
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__skb_queue_tail(TX_QUEUE(sk), skb);
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if (pi->mode == L2CAP_MODE_ERTM)
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spin_lock_bh(&pi->send_lock);
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if (sk->sk_send_head == NULL)
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sk->sk_send_head = skb;
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if (pi->mode == L2CAP_MODE_ERTM)
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spin_unlock_bh(&pi->send_lock);
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} else {
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/* Segment SDU into multiples PDUs */
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err = l2cap_sar_segment_sdu(sk, msg, len);
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@ -1754,10 +1789,13 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms
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goto done;
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}
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if (pi->mode == L2CAP_MODE_STREAMING)
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if (pi->mode == L2CAP_MODE_STREAMING) {
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err = l2cap_streaming_send(sk);
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else
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} else {
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spin_lock_bh(&pi->send_lock);
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err = l2cap_ertm_send(sk);
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spin_unlock_bh(&pi->send_lock);
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}
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if (err >= 0)
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err = len;
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@ -2321,6 +2359,7 @@ static inline void l2cap_ertm_init(struct sock *sk)
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__skb_queue_head_init(SREJ_QUEUE(sk));
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__skb_queue_head_init(BUSY_QUEUE(sk));
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spin_lock_init(&l2cap_pi(sk)->send_lock);
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INIT_WORK(&l2cap_pi(sk)->busy_work, l2cap_busy_work);
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}
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@ -3340,7 +3379,9 @@ static inline void l2cap_send_i_or_rr_or_rnr(struct sock *sk)
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if (pi->conn_state & L2CAP_CONN_REMOTE_BUSY && pi->unacked_frames > 0)
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__mod_retrans_timer();
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spin_lock_bh(&pi->send_lock);
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l2cap_ertm_send(sk);
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spin_unlock_bh(&pi->send_lock);
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if (!(pi->conn_state & L2CAP_CONN_LOCAL_BUSY) &&
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pi->frames_sent == 0) {
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@ -3857,12 +3898,8 @@ static inline int l2cap_data_channel_iframe(struct sock *sk, u16 rx_control, str
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if (rx_control & L2CAP_CTRL_FINAL) {
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if (pi->conn_state & L2CAP_CONN_REJ_ACT)
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pi->conn_state &= ~L2CAP_CONN_REJ_ACT;
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else {
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if (!skb_queue_empty(TX_QUEUE(sk)))
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sk->sk_send_head = TX_QUEUE(sk)->next;
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pi->next_tx_seq = pi->expected_ack_seq;
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l2cap_ertm_send(sk);
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}
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else
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l2cap_retransmit_frames(sk);
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}
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err = l2cap_push_rx_skb(sk, skb, rx_control);
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@ -3907,12 +3944,8 @@ static inline void l2cap_data_channel_rrframe(struct sock *sk, u16 rx_control)
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if (pi->conn_state & L2CAP_CONN_REJ_ACT)
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pi->conn_state &= ~L2CAP_CONN_REJ_ACT;
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else {
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if (!skb_queue_empty(TX_QUEUE(sk)))
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sk->sk_send_head = TX_QUEUE(sk)->next;
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pi->next_tx_seq = pi->expected_ack_seq;
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l2cap_ertm_send(sk);
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}
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else
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l2cap_retransmit_frames(sk);
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} else {
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if ((pi->conn_state & L2CAP_CONN_REMOTE_BUSY) &&
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@ -3920,10 +3953,13 @@ static inline void l2cap_data_channel_rrframe(struct sock *sk, u16 rx_control)
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__mod_retrans_timer();
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pi->conn_state &= ~L2CAP_CONN_REMOTE_BUSY;
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if (pi->conn_state & L2CAP_CONN_SREJ_SENT)
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if (pi->conn_state & L2CAP_CONN_SREJ_SENT) {
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l2cap_send_ack(pi);
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else
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} else {
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spin_lock_bh(&pi->send_lock);
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l2cap_ertm_send(sk);
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spin_unlock_bh(&pi->send_lock);
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}
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}
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}
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@ -3940,17 +3976,10 @@ static inline void l2cap_data_channel_rejframe(struct sock *sk, u16 rx_control)
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if (rx_control & L2CAP_CTRL_FINAL) {
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if (pi->conn_state & L2CAP_CONN_REJ_ACT)
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pi->conn_state &= ~L2CAP_CONN_REJ_ACT;
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else {
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if (!skb_queue_empty(TX_QUEUE(sk)))
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sk->sk_send_head = TX_QUEUE(sk)->next;
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pi->next_tx_seq = pi->expected_ack_seq;
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l2cap_ertm_send(sk);
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}
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else
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l2cap_retransmit_frames(sk);
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} else {
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if (!skb_queue_empty(TX_QUEUE(sk)))
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sk->sk_send_head = TX_QUEUE(sk)->next;
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pi->next_tx_seq = pi->expected_ack_seq;
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l2cap_ertm_send(sk);
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l2cap_retransmit_frames(sk);
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if (pi->conn_state & L2CAP_CONN_WAIT_F)
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pi->conn_state |= L2CAP_CONN_REJ_ACT;
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@ -3966,8 +3995,12 @@ static inline void l2cap_data_channel_srejframe(struct sock *sk, u16 rx_control)
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if (rx_control & L2CAP_CTRL_POLL) {
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pi->expected_ack_seq = tx_seq;
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l2cap_drop_acked_frames(sk);
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l2cap_retransmit_frame(sk, tx_seq);
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l2cap_retransmit_one_frame(sk, tx_seq);
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spin_lock_bh(&pi->send_lock);
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l2cap_ertm_send(sk);
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spin_unlock_bh(&pi->send_lock);
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if (pi->conn_state & L2CAP_CONN_WAIT_F) {
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pi->srej_save_reqseq = tx_seq;
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pi->conn_state |= L2CAP_CONN_SREJ_ACT;
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@ -3977,9 +4010,9 @@ static inline void l2cap_data_channel_srejframe(struct sock *sk, u16 rx_control)
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pi->srej_save_reqseq == tx_seq)
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pi->conn_state &= ~L2CAP_CONN_SREJ_ACT;
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else
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l2cap_retransmit_frame(sk, tx_seq);
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l2cap_retransmit_one_frame(sk, tx_seq);
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} else {
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l2cap_retransmit_frame(sk, tx_seq);
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l2cap_retransmit_one_frame(sk, tx_seq);
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if (pi->conn_state & L2CAP_CONN_WAIT_F) {
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pi->srej_save_reqseq = tx_seq;
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pi->conn_state |= L2CAP_CONN_SREJ_ACT;
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