Hi Andrei, * Emeltchenko Andrei <Andrei.Emeltchenko.news@xxxxxxxxx> [2010-10-29 16:43:00 +0300]: > From: Andrei Emeltchenko <andrei.emeltchenko@xxxxxxxxx> > > Check that socket sk is not locked in user process before removing > l2cap connection handler. > > lock_sock and release_sock do not hold a normal spinlock directly but > instead hold the owner field. This means bh_lock_sock can still execute > even if the socket is "locked". More info can be found here: > http://www.linuxfoundation.org/collaborate/workgroups/networking/socketlocks > > krfcommd kernel thread may be preempted with l2cap tasklet which remove > l2cap_conn structure. If krfcommd is in process of sending of RFCOMM reply > (like "RFCOMM UA" reply to "RFCOMM DISC") then kernel crash happens. > > ... > [ 694.175933] Unable to handle kernel NULL pointer dereference at virtual address 00000000 > [ 694.184936] pgd = c0004000 > [ 694.187683] [00000000] *pgd=00000000 > [ 694.191711] Internal error: Oops: 5 [#1] PREEMPT > [ 694.196350] last sysfs file: /sys/devices/platform/hci_h4p/firmware/hci_h4p/loading > [ 694.260375] CPU: 0 Not tainted (2.6.32.10 #1) > [ 694.265106] PC is at l2cap_sock_sendmsg+0x43c/0x73c [l2cap] > [ 694.270721] LR is at 0xd7017303 > ... > [ 694.525085] Backtrace: > [ 694.527587] [<bf266be0>] (l2cap_sock_sendmsg+0x0/0x73c [l2cap]) from [<c02f2cc8>] (sock_sendmsg+0xb8/0xd8) > [ 694.537292] [<c02f2c10>] (sock_sendmsg+0x0/0xd8) from [<c02f3044>] (kernel_sendmsg+0x48/0x80) > > Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@xxxxxxxxx> > --- > net/bluetooth/l2cap.c | 26 ++++++++++++++++++++++++++ > 1 files changed, 26 insertions(+), 0 deletions(-) > > diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c > index 6f931cc..b1344d8 100644 > --- a/net/bluetooth/l2cap.c > +++ b/net/bluetooth/l2cap.c > @@ -3078,6 +3078,14 @@ static inline int l2cap_connect_rsp(struct l2cap_conn *conn, struct l2cap_cmd_hd > break; > > default: > + /* don't delete l2cap channel if sk is owned by user */ > + if (sock_owned_by_user(sk)) { > + sk->sk_state = BT_DISCONN; > + l2cap_sock_clear_timer(sk); > + l2cap_sock_set_timer(sk, HZ); > + break; > + } > + > l2cap_chan_del(sk, ECONNREFUSED); > break; > } > @@ -3283,6 +3291,15 @@ static inline int l2cap_disconnect_req(struct l2cap_conn *conn, struct l2cap_cmd > > sk->sk_shutdown = SHUTDOWN_MASK; > > + /* don't delete l2cap channel if sk is owned by user */ > + if (sock_owned_by_user(sk)) { > + sk->sk_state = BT_DISCONN; > + l2cap_sock_clear_timer(sk); > + l2cap_sock_set_timer(sk, HZ); > + bh_unlock_sock(sk); > + return 0; > + } > + > l2cap_chan_del(sk, ECONNRESET); > bh_unlock_sock(sk); > > @@ -3305,6 +3322,15 @@ static inline int l2cap_disconnect_rsp(struct l2cap_conn *conn, struct l2cap_cmd > if (!sk) > return 0; > > + /* don't delete l2cap channel if sk is owned by user */ > + if (sock_owned_by_user(sk)) { > + sk->sk_state = BT_DISCONN; > + l2cap_sock_clear_timer(sk); > + l2cap_sock_set_timer(sk, HZ); 1 second is too much. Change it to HZ/5 as well. I think it is a reasonable value. -- Gustavo F. Padovan ProFUSION embedded systems - http://profusion.mobi -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
