From d37f50e19094862a5d60d79637d6f4dbdc42f4f1 Mon Sep 17 00:00:00 2001 From: Andrei Emeltchenko Date: Mon, 24 Jan 2011 10:53:24 +0200 Subject: [PATCH] Bluetooth: fix crash by disabling tasklet in sock accept Crash can happen when tasklet handling connect/disconnect requests preempts socket accept. Can be reproduced with "l2test -r" on one side and several "l2test -c -b 1000 -i hci0 -P 10 " on the other side. disable taskets in socket accept and change lock_sock and release_sock to bh_lock_sock and bh_unlock_sock since we have to use spinlocks and there is no need to mark sock as owned by user. ... [ 3555.897247] Unable to handle kernel NULL pointer dereference at virtual address 000000bc [ 3555.915039] pgd = cab9c000 [ 3555.917785] [000000bc] *pgd=8bf3d031, *pte=00000000, *ppte=00000000 [ 3555.928314] Internal error: Oops: 17 [#1] PREEMPT [ 3555.999786] CPU: 0 Not tainted (2.6.32.21-13874-g67918ef #65) ... [ 3556.005981] PC is at bt_accept_unlink+0x20/0x58 [bluetooth] [ 3556.011627] LR is at bt_accept_dequeue+0x3c/0xe8 [bluetooth] ... [ 3556.161285] [] (bt_accept_unlink+0x20/0x58 [bluetooth]) from [] (bt_accept_dequeue+0x3c/0xe8 [bluetooth]) [ 3556.172729] [] (bt_accept_dequeue+0x3c/0xe8 [bluetooth]) from [] (l2cap_sock_accept+0x100/0x15c [l2cap]) [ 3556.184082] [] (l2cap_sock_accept+0x100/0x15c [l2cap]) from [] (sys_accept4+0x120/0x1e0) [ 3556.193969] [] (sys_accept4+0x120/0x1e0) from [] (ret_fast_syscall+0x0/0x2c) [ 3556.202819] Code: e5813000 e5901164 e580c160 e580c15c (e1d13bbc) ... Signed-off-by: Andrei Emeltchenko Signed-off-by: Gustavo F. Padovan --- net/bluetooth/af_bluetooth.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c index a6732b576a52..2abfe2f30453 100644 --- a/net/bluetooth/af_bluetooth.c +++ b/net/bluetooth/af_bluetooth.c @@ -199,14 +199,15 @@ struct sock *bt_accept_dequeue(struct sock *parent, struct socket *newsock) BT_DBG("parent %p", parent); + local_bh_disable(); list_for_each_safe(p, n, &bt_sk(parent)->accept_q) { sk = (struct sock *) list_entry(p, struct bt_sock, accept_q); - lock_sock(sk); + bh_lock_sock(sk); /* FIXME: Is this check still needed */ if (sk->sk_state == BT_CLOSED) { - release_sock(sk); + bh_unlock_sock(sk); bt_accept_unlink(sk); continue; } @@ -216,12 +217,16 @@ struct sock *bt_accept_dequeue(struct sock *parent, struct socket *newsock) bt_accept_unlink(sk); if (newsock) sock_graft(sk, newsock); - release_sock(sk); + + bh_unlock_sock(sk); + local_bh_enable(); return sk; } - release_sock(sk); + bh_unlock_sock(sk); } + local_bh_enable(); + return NULL; } EXPORT_SYMBOL(bt_accept_dequeue); -- 2.20.1