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    Subject[PATCH 6.0 708/862] Bluetooth: L2CAP: initialize delayed works at l2cap_chan_create()
    Date
    From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

    [ Upstream commit 2d2cb3066f2c90cd8ca540b36ba7a55e7f2406e0 ]

    syzbot is reporting cancel_delayed_work() without INIT_DELAYED_WORK() at
    l2cap_chan_del() [1], for CONF_NOT_COMPLETE flag (which meant to prevent
    l2cap_chan_del() from calling cancel_delayed_work()) is cleared by timer
    which fires before l2cap_chan_del() is called by closing file descriptor
    created by socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_L2CAP).

    l2cap_bredr_sig_cmd(L2CAP_CONF_REQ) and l2cap_bredr_sig_cmd(L2CAP_CONF_RSP)
    are calling l2cap_ertm_init(chan), and they call l2cap_chan_ready() (which
    clears CONF_NOT_COMPLETE flag) only when l2cap_ertm_init(chan) succeeded.

    l2cap_sock_init() does not call l2cap_ertm_init(chan), and it instead sets
    CONF_NOT_COMPLETE flag by calling l2cap_chan_set_defaults(). However, when
    connect() is requested, "command 0x0409 tx timeout" happens after 2 seconds
    from connect() request, and CONF_NOT_COMPLETE flag is cleared after 4
    seconds from connect() request, for l2cap_conn_start() from
    l2cap_info_timeout() callback scheduled by

    schedule_delayed_work(&conn->info_timer, L2CAP_INFO_TIMEOUT);

    in l2cap_connect() is calling l2cap_chan_ready().

    Fix this problem by initializing delayed works used by L2CAP_MODE_ERTM
    mode as soon as l2cap_chan_create() allocates a channel, like I did in
    commit be8597239379f0f5 ("Bluetooth: initialize skb_queue_head at
    l2cap_chan_create()").

    Link: https://syzkaller.appspot.com/bug?extid=83672956c7aa6af698b3 [1]
    Reported-by: syzbot <syzbot+83672956c7aa6af698b3@syzkaller.appspotmail.com>
    Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
    Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/bluetooth/l2cap_core.c | 10 ++++++----
    1 file changed, 6 insertions(+), 4 deletions(-)

    diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
    index 2c9de67daadc..770891f68703 100644
    --- a/net/bluetooth/l2cap_core.c
    +++ b/net/bluetooth/l2cap_core.c
    @@ -61,6 +61,9 @@ static void l2cap_send_disconn_req(struct l2cap_chan *chan, int err);

    static void l2cap_tx(struct l2cap_chan *chan, struct l2cap_ctrl *control,
    struct sk_buff_head *skbs, u8 event);
    +static void l2cap_retrans_timeout(struct work_struct *work);
    +static void l2cap_monitor_timeout(struct work_struct *work);
    +static void l2cap_ack_timeout(struct work_struct *work);

    static inline u8 bdaddr_type(u8 link_type, u8 bdaddr_type)
    {
    @@ -476,6 +479,9 @@ struct l2cap_chan *l2cap_chan_create(void)
    write_unlock(&chan_list_lock);

    INIT_DELAYED_WORK(&chan->chan_timer, l2cap_chan_timeout);
    + INIT_DELAYED_WORK(&chan->retrans_timer, l2cap_retrans_timeout);
    + INIT_DELAYED_WORK(&chan->monitor_timer, l2cap_monitor_timeout);
    + INIT_DELAYED_WORK(&chan->ack_timer, l2cap_ack_timeout);

    chan->state = BT_OPEN;

    @@ -3320,10 +3326,6 @@ int l2cap_ertm_init(struct l2cap_chan *chan)
    chan->rx_state = L2CAP_RX_STATE_RECV;
    chan->tx_state = L2CAP_TX_STATE_XMIT;

    - INIT_DELAYED_WORK(&chan->retrans_timer, l2cap_retrans_timeout);
    - INIT_DELAYED_WORK(&chan->monitor_timer, l2cap_monitor_timeout);
    - INIT_DELAYED_WORK(&chan->ack_timer, l2cap_ack_timeout);
    -
    skb_queue_head_init(&chan->srej_q);

    err = l2cap_seq_list_init(&chan->srej_list, chan->tx_win);
    --
    2.35.1


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