From dfc909befbfe967bd7f46ef33b6969c1b7f3cf42 Mon Sep 17 00:00:00 2001 From: "Gustavo F. Padovan" Date: Sat, 1 May 2010 16:15:45 -0300 Subject: [PATCH] Bluetooth: Fix race condition on l2cap_ertm_send() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: João Paulo Rechi Vita Signed-off-by: Marcel Holtmann --- include/net/bluetooth/l2cap.h | 1 + net/bluetooth/l2cap.c | 99 +++++++++++++++++++++++------------ 2 files changed, 67 insertions(+), 33 deletions(-) diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h index d0185cc04c14..7c695bfd853c 100644 --- a/include/net/bluetooth/l2cap.h +++ b/include/net/bluetooth/l2cap.h @@ -353,6 +353,7 @@ struct l2cap_pinfo { __le16 sport; + spinlock_t send_lock; struct timer_list retrans_timer; struct timer_list monitor_timer; struct timer_list ack_timer; diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c index 9d514f9dbc0f..fe663e9c6684 100644 --- a/net/bluetooth/l2cap.c +++ b/net/bluetooth/l2cap.c @@ -1368,7 +1368,7 @@ static int l2cap_streaming_send(struct sock *sk) return 0; } -static void l2cap_retransmit_frame(struct sock *sk, u8 tx_seq) +static void l2cap_retransmit_one_frame(struct sock *sk, u8 tx_seq) { struct l2cap_pinfo *pi = l2cap_pi(sk); struct sk_buff *skb, *tx_skb; @@ -1467,10 +1467,29 @@ static int l2cap_ertm_send(struct sock *sk) return nsent; } +static int l2cap_retransmit_frames(struct sock *sk) +{ + struct l2cap_pinfo *pi = l2cap_pi(sk); + int ret; + + spin_lock_bh(&pi->send_lock); + + if (!skb_queue_empty(TX_QUEUE(sk))) + sk->sk_send_head = TX_QUEUE(sk)->next; + + pi->next_tx_seq = pi->expected_ack_seq; + ret = l2cap_ertm_send(sk); + + spin_unlock_bh(&pi->send_lock); + + return ret; +} + static void l2cap_send_ack(struct l2cap_pinfo *pi) { struct sock *sk = (struct sock *)pi; u16 control = 0; + int nframes; control |= pi->buffer_seq << L2CAP_CTRL_REQSEQ_SHIFT; @@ -1479,10 +1498,17 @@ static void l2cap_send_ack(struct l2cap_pinfo *pi) pi->conn_state |= L2CAP_CONN_RNR_SENT; l2cap_send_sframe(pi, control); return; - } else if (l2cap_ertm_send(sk) == 0) { - control |= L2CAP_SUPER_RCV_READY; - l2cap_send_sframe(pi, control); } + + spin_lock_bh(&pi->send_lock); + nframes = l2cap_ertm_send(sk); + spin_unlock_bh(&pi->send_lock); + + if (nframes > 0) + return; + + control |= L2CAP_SUPER_RCV_READY; + l2cap_send_sframe(pi, control); } static void l2cap_send_srejtail(struct sock *sk) @@ -1673,8 +1699,10 @@ static inline int l2cap_sar_segment_sdu(struct sock *sk, struct msghdr *msg, siz size += buflen; } skb_queue_splice_tail(&sar_queue, TX_QUEUE(sk)); + spin_lock_bh(&pi->send_lock); if (sk->sk_send_head == NULL) sk->sk_send_head = sar_queue.next; + spin_unlock_bh(&pi->send_lock); return size; } @@ -1745,8 +1773,15 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms goto done; } __skb_queue_tail(TX_QUEUE(sk), skb); + + if (pi->mode == L2CAP_MODE_ERTM) + spin_lock_bh(&pi->send_lock); + if (sk->sk_send_head == NULL) sk->sk_send_head = skb; + + if (pi->mode == L2CAP_MODE_ERTM) + spin_unlock_bh(&pi->send_lock); } else { /* Segment SDU into multiples PDUs */ err = l2cap_sar_segment_sdu(sk, msg, len); @@ -1754,10 +1789,13 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms goto done; } - if (pi->mode == L2CAP_MODE_STREAMING) + if (pi->mode == L2CAP_MODE_STREAMING) { err = l2cap_streaming_send(sk); - else + } else { + spin_lock_bh(&pi->send_lock); err = l2cap_ertm_send(sk); + spin_unlock_bh(&pi->send_lock); + } if (err >= 0) err = len; @@ -2321,6 +2359,7 @@ static inline void l2cap_ertm_init(struct sock *sk) __skb_queue_head_init(SREJ_QUEUE(sk)); __skb_queue_head_init(BUSY_QUEUE(sk)); + spin_lock_init(&l2cap_pi(sk)->send_lock); INIT_WORK(&l2cap_pi(sk)->busy_work, l2cap_busy_work); } @@ -3340,7 +3379,9 @@ static inline void l2cap_send_i_or_rr_or_rnr(struct sock *sk) if (pi->conn_state & L2CAP_CONN_REMOTE_BUSY && pi->unacked_frames > 0) __mod_retrans_timer(); + spin_lock_bh(&pi->send_lock); l2cap_ertm_send(sk); + spin_unlock_bh(&pi->send_lock); if (!(pi->conn_state & L2CAP_CONN_LOCAL_BUSY) && pi->frames_sent == 0) { @@ -3857,12 +3898,8 @@ expected: if (rx_control & L2CAP_CTRL_FINAL) { if (pi->conn_state & L2CAP_CONN_REJ_ACT) pi->conn_state &= ~L2CAP_CONN_REJ_ACT; - else { - 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 + l2cap_retransmit_frames(sk); } err = l2cap_push_rx_skb(sk, skb, rx_control); @@ -3907,12 +3944,8 @@ 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 { - 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 + l2cap_retransmit_frames(sk); } else { if ((pi->conn_state & L2CAP_CONN_REMOTE_BUSY) && @@ -3920,10 +3953,13 @@ static inline void l2cap_data_channel_rrframe(struct sock *sk, u16 rx_control) __mod_retrans_timer(); pi->conn_state &= ~L2CAP_CONN_REMOTE_BUSY; - if (pi->conn_state & L2CAP_CONN_SREJ_SENT) + if (pi->conn_state & L2CAP_CONN_SREJ_SENT) { l2cap_send_ack(pi); - else + } else { + spin_lock_bh(&pi->send_lock); l2cap_ertm_send(sk); + spin_unlock_bh(&pi->send_lock); + } } } @@ -3940,17 +3976,10 @@ static inline void l2cap_data_channel_rejframe(struct sock *sk, u16 rx_control) if (rx_control & L2CAP_CTRL_FINAL) { if (pi->conn_state & L2CAP_CONN_REJ_ACT) pi->conn_state &= ~L2CAP_CONN_REJ_ACT; - else { - 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 + l2cap_retransmit_frames(sk); } else { - 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); + l2cap_retransmit_frames(sk); if (pi->conn_state & L2CAP_CONN_WAIT_F) pi->conn_state |= L2CAP_CONN_REJ_ACT; @@ -3966,8 +3995,12 @@ static inline void l2cap_data_channel_srejframe(struct sock *sk, u16 rx_control) if (rx_control & L2CAP_CTRL_POLL) { pi->expected_ack_seq = tx_seq; l2cap_drop_acked_frames(sk); - l2cap_retransmit_frame(sk, tx_seq); + l2cap_retransmit_one_frame(sk, tx_seq); + + spin_lock_bh(&pi->send_lock); l2cap_ertm_send(sk); + spin_unlock_bh(&pi->send_lock); + if (pi->conn_state & L2CAP_CONN_WAIT_F) { pi->srej_save_reqseq = tx_seq; pi->conn_state |= L2CAP_CONN_SREJ_ACT; @@ -3977,9 +4010,9 @@ static inline void l2cap_data_channel_srejframe(struct sock *sk, u16 rx_control) pi->srej_save_reqseq == tx_seq) pi->conn_state &= ~L2CAP_CONN_SREJ_ACT; else - l2cap_retransmit_frame(sk, tx_seq); + l2cap_retransmit_one_frame(sk, tx_seq); } else { - l2cap_retransmit_frame(sk, tx_seq); + l2cap_retransmit_one_frame(sk, tx_seq); if (pi->conn_state & L2CAP_CONN_WAIT_F) { pi->srej_save_reqseq = tx_seq; pi->conn_state |= L2CAP_CONN_SREJ_ACT; -- 2.20.1