l2tp: must disable bh before calling l2tp_xmit_skb()
François Cachereul made a very nice bug report and suspected
the bh_lock_sock() / bh_unlok_sock() pair used in l2tp_xmit_skb() from
process context was not good.
This problem was added by commit 6af88da14ee284aaad6e4326da09a89191ab6165
("l2tp: Fix locking in l2tp_core.c").
l2tp_eth_dev_xmit() runs from BH context, so we must disable BH
from other l2tp_xmit_skb() users.
[ 452.060011] BUG: soft lockup - CPU#1 stuck for 23s! [accel-pppd:6662]
[ 452.061757] Modules linked in: l2tp_ppp l2tp_netlink l2tp_core pppoe pppox
ppp_generic slhc ipv6 ext3 mbcache jbd virtio_balloon xfs exportfs dm_mod
virtio_blk ata_generic virtio_net floppy ata_piix libata virtio_pci virtio_ring virtio [last unloaded: scsi_wait_scan]
[ 452.064012] CPU 1
[ 452.080015] BUG: soft lockup - CPU#2 stuck for 23s! [accel-pppd:6643]
[ 452.080015] CPU 2
[ 452.080015]
[ 452.080015] Pid: 6643, comm: accel-pppd Not tainted 3.2.46.mini #1 Bochs Bochs
[ 452.080015] RIP: 0010:[<ffffffff81059f6c>] [<ffffffff81059f6c>] do_raw_spin_lock+0x17/0x1f
[ 452.080015] RSP: 0018:ffff88007125fc18 EFLAGS: 00000293
[ 452.080015] RAX: 000000000000aba9 RBX: ffffffff811d0703 RCX: 0000000000000000
[ 452.080015] RDX: 00000000000000ab RSI: ffff8800711f6896 RDI: ffff8800745c8110
[ 452.080015] RBP: ffff88007125fc18 R08: 0000000000000020 R09: 0000000000000000
[ 452.080015] R10: 0000000000000000 R11: 0000000000000280 R12: 0000000000000286
[ 452.080015] R13: 0000000000000020 R14: 0000000000000240 R15: 0000000000000000
[ 452.080015] FS: 00007fdc0cc24700(0000) GS:ffff8800b6f00000(0000) knlGS:0000000000000000
[ 452.080015] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 452.080015] CR2: 00007fdb054899b8 CR3: 0000000074404000 CR4: 00000000000006a0
[ 452.080015] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 452.080015] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 452.080015] Process accel-pppd (pid: 6643, threadinfo ffff88007125e000, task ffff8800b27e6dd0)
[ 452.080015] Stack:
[ 452.080015] ffff88007125fc28 ffffffff81256559 ffff88007125fc98 ffffffffa01b2bd1
[ 452.080015] ffff88007125fc58 000000000000000c 00000000029490d0 0000009c71dbe25e
[ 452.080015] 000000000000005c 000000080000000e 0000000000000000 ffff880071170600
[ 452.080015] Call Trace:
[ 452.080015] [<ffffffff81256559>] _raw_spin_lock+0xe/0x10
[ 452.080015] [<ffffffffa01b2bd1>] l2tp_xmit_skb+0x189/0x4ac [l2tp_core]
[ 452.080015] [<ffffffffa01c2d36>] pppol2tp_sendmsg+0x15e/0x19c [l2tp_ppp]
[ 452.080015] [<ffffffff811c7872>] __sock_sendmsg_nosec+0x22/0x24
[ 452.080015] [<ffffffff811c83bd>] sock_sendmsg+0xa1/0xb6
[ 452.080015] [<ffffffff81254e88>] ? __schedule+0x5c1/0x616
[ 452.080015] [<ffffffff8103c7c6>] ? __dequeue_signal+0xb7/0x10c
[ 452.080015] [<ffffffff810bbd21>] ? fget_light+0x75/0x89
[ 452.080015] [<ffffffff811c8444>] ? sockfd_lookup_light+0x20/0x56
[ 452.080015] [<ffffffff811c9b34>] sys_sendto+0x10c/0x13b
[ 452.080015] [<ffffffff8125cac2>] system_call_fastpath+0x16/0x1b
[ 452.080015] Code: 81 48 89 e5 72 0c 31 c0 48 81 ff 45 66 25 81 0f 92 c0 5d c3 55 b8 00 01 00 00 48 89 e5 f0 66 0f c1 07 0f b6 d4 38 d0 74 06 f3 90 <8a> 07 eb f6 5d c3 90 90 55 48 89 e5 9c 58 0f 1f 44 00 00 5d c3
[ 452.080015] Call Trace:
[ 452.080015] [<ffffffff81256559>] _raw_spin_lock+0xe/0x10
[ 452.080015] [<ffffffffa01b2bd1>] l2tp_xmit_skb+0x189/0x4ac [l2tp_core]
[ 452.080015] [<ffffffffa01c2d36>] pppol2tp_sendmsg+0x15e/0x19c [l2tp_ppp]
[ 452.080015] [<ffffffff811c7872>] __sock_sendmsg_nosec+0x22/0x24
[ 452.080015] [<ffffffff811c83bd>] sock_sendmsg+0xa1/0xb6
[ 452.080015] [<ffffffff81254e88>] ? __schedule+0x5c1/0x616
[ 452.080015] [<ffffffff8103c7c6>] ? __dequeue_signal+0xb7/0x10c
[ 452.080015] [<ffffffff810bbd21>] ? fget_light+0x75/0x89
[ 452.080015] [<ffffffff811c8444>] ? sockfd_lookup_light+0x20/0x56
[ 452.080015] [<ffffffff811c9b34>] sys_sendto+0x10c/0x13b
[ 452.080015] [<ffffffff8125cac2>] system_call_fastpath+0x16/0x1b
[ 452.064012]
[ 452.064012] Pid: 6662, comm: accel-pppd Not tainted 3.2.46.mini #1 Bochs Bochs
[ 452.064012] RIP: 0010:[<ffffffff81059f6e>] [<ffffffff81059f6e>] do_raw_spin_lock+0x19/0x1f
[ 452.064012] RSP: 0018:ffff8800b6e83ba0 EFLAGS: 00000297
[ 452.064012] RAX: 000000000000aaa9 RBX: ffff8800b6e83b40 RCX: 0000000000000002
[ 452.064012] RDX: 00000000000000aa RSI: 000000000000000a RDI: ffff8800745c8110
[ 452.064012] RBP: ffff8800b6e83ba0 R08: 000000000000c802 R09: 000000000000001c
[ 452.064012] R10: ffff880071096c4e R11: 0000000000000006 R12: ffff8800b6e83b18
[ 452.064012] R13: ffffffff8125d51e R14: ffff8800b6e83ba0 R15: ffff880072a589c0
[ 452.064012] FS: 00007fdc0b81e700(0000) GS:ffff8800b6e80000(0000) knlGS:0000000000000000
[ 452.064012] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 452.064012] CR2: 0000000000625208 CR3: 0000000074404000 CR4: 00000000000006a0
[ 452.064012] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 452.064012] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 452.064012] Process accel-pppd (pid: 6662, threadinfo ffff88007129a000, task ffff8800744f7410)
[ 452.064012] Stack:
[ 452.064012] ffff8800b6e83bb0 ffffffff81256559 ffff8800b6e83bc0 ffffffff8121c64a
[ 452.064012] ffff8800b6e83bf0 ffffffff8121ec7a ffff880072a589c0 ffff880071096c62
[ 452.064012] 0000000000000011 ffffffff81430024 ffff8800b6e83c80 ffffffff8121f276
[ 452.064012] Call Trace:
[ 452.064012] <IRQ>
[ 452.064012] [<ffffffff81256559>] _raw_spin_lock+0xe/0x10
[ 452.064012] [<ffffffff8121c64a>] spin_lock+0x9/0xb
[ 452.064012] [<ffffffff8121ec7a>] udp_queue_rcv_skb+0x186/0x269
[ 452.064012] [<ffffffff8121f276>] __udp4_lib_rcv+0x297/0x4ae
[ 452.064012] [<ffffffff8121c178>] ? raw_rcv+0xe9/0xf0
[ 452.064012] [<ffffffff8121f4a7>] udp_rcv+0x1a/0x1c
[ 452.064012] [<ffffffff811fe385>] ip_local_deliver_finish+0x12b/0x1a5
[ 452.064012] [<ffffffff811fe54e>] ip_local_deliver+0x53/0x84
[ 452.064012] [<ffffffff811fe1d0>] ip_rcv_finish+0x2bc/0x2f3
[ 452.064012] [<ffffffff811fe78f>] ip_rcv+0x210/0x269
[ 452.064012] [<ffffffff8101911e>] ? kvm_clock_get_cycles+0x9/0xb
[ 452.064012] [<ffffffff811d88cd>] __netif_receive_skb+0x3a5/0x3f7
[ 452.064012] [<ffffffff811d8eba>] netif_receive_skb+0x57/0x5e
[ 452.064012] [<ffffffff811cf30f>] ? __netdev_alloc_skb+0x1f/0x3b
[ 452.064012] [<ffffffffa0049126>] virtnet_poll+0x4ba/0x5a4 [virtio_net]
[ 452.064012] [<ffffffff811d9417>] net_rx_action+0x73/0x184
[ 452.064012] [<ffffffffa01b2cc2>] ? l2tp_xmit_skb+0x27a/0x4ac [l2tp_core]
[ 452.064012] [<ffffffff810343b9>] __do_softirq+0xc3/0x1a8
[ 452.064012] [<ffffffff81013b56>] ? ack_APIC_irq+0x10/0x12
[ 452.064012] [<ffffffff81256559>] ? _raw_spin_lock+0xe/0x10
[ 452.064012] [<ffffffff8125e0ac>] call_softirq+0x1c/0x26
[ 452.064012] [<ffffffff81003587>] do_softirq+0x45/0x82
[ 452.064012] [<ffffffff81034667>] irq_exit+0x42/0x9c
[ 452.064012] [<ffffffff8125e146>] do_IRQ+0x8e/0xa5
[ 452.064012] [<ffffffff8125676e>] common_interrupt+0x6e/0x6e
[ 452.064012] <EOI>
[ 452.064012] [<ffffffff810b82a1>] ? kfree+0x8a/0xa3
[ 452.064012] [<ffffffffa01b2cc2>] ? l2tp_xmit_skb+0x27a/0x4ac [l2tp_core]
[ 452.064012] [<ffffffffa01b2c25>] ? l2tp_xmit_skb+0x1dd/0x4ac [l2tp_core]
[ 452.064012] [<ffffffffa01c2d36>] pppol2tp_sendmsg+0x15e/0x19c [l2tp_ppp]
[ 452.064012] [<ffffffff811c7872>] __sock_sendmsg_nosec+0x22/0x24
[ 452.064012] [<ffffffff811c83bd>] sock_sendmsg+0xa1/0xb6
[ 452.064012] [<ffffffff81254e88>] ? __schedule+0x5c1/0x616
[ 452.064012] [<ffffffff8103c7c6>] ? __dequeue_signal+0xb7/0x10c
[ 452.064012] [<ffffffff810bbd21>] ? fget_light+0x75/0x89
[ 452.064012] [<ffffffff811c8444>] ? sockfd_lookup_light+0x20/0x56
[ 452.064012] [<ffffffff811c9b34>] sys_sendto+0x10c/0x13b
[ 452.064012] [<ffffffff8125cac2>] system_call_fastpath+0x16/0x1b
[ 452.064012] Code: 89 e5 72 0c 31 c0 48 81 ff 45 66 25 81 0f 92 c0 5d c3 55 b8 00 01 00 00 48 89 e5 f0 66 0f c1 07 0f b6 d4 38 d0 74 06 f3 90 8a 07 <eb> f6 5d c3 90 90 55 48 89 e5 9c 58 0f 1f 44 00 00 5d c3 55 48
[ 452.064012] Call Trace:
[ 452.064012] <IRQ> [<ffffffff81256559>] _raw_spin_lock+0xe/0x10
[ 452.064012] [<ffffffff8121c64a>] spin_lock+0x9/0xb
[ 452.064012] [<ffffffff8121ec7a>] udp_queue_rcv_skb+0x186/0x269
[ 452.064012] [<ffffffff8121f276>] __udp4_lib_rcv+0x297/0x4ae
[ 452.064012] [<ffffffff8121c178>] ? raw_rcv+0xe9/0xf0
[ 452.064012] [<ffffffff8121f4a7>] udp_rcv+0x1a/0x1c
[ 452.064012] [<ffffffff811fe385>] ip_local_deliver_finish+0x12b/0x1a5
[ 452.064012] [<ffffffff811fe54e>] ip_local_deliver+0x53/0x84
[ 452.064012] [<ffffffff811fe1d0>] ip_rcv_finish+0x2bc/0x2f3
[ 452.064012] [<ffffffff811fe78f>] ip_rcv+0x210/0x269
[ 452.064012] [<ffffffff8101911e>] ? kvm_clock_get_cycles+0x9/0xb
[ 452.064012] [<ffffffff811d88cd>] __netif_receive_skb+0x3a5/0x3f7
[ 452.064012] [<ffffffff811d8eba>] netif_receive_skb+0x57/0x5e
[ 452.064012] [<ffffffff811cf30f>] ? __netdev_alloc_skb+0x1f/0x3b
[ 452.064012] [<ffffffffa0049126>] virtnet_poll+0x4ba/0x5a4 [virtio_net]
[ 452.064012] [<ffffffff811d9417>] net_rx_action+0x73/0x184
[ 452.064012] [<ffffffffa01b2cc2>] ? l2tp_xmit_skb+0x27a/0x4ac [l2tp_core]
[ 452.064012] [<ffffffff810343b9>] __do_softirq+0xc3/0x1a8
[ 452.064012] [<ffffffff81013b56>] ? ack_APIC_irq+0x10/0x12
[ 452.064012] [<ffffffff81256559>] ? _raw_spin_lock+0xe/0x10
[ 452.064012] [<ffffffff8125e0ac>] call_softirq+0x1c/0x26
[ 452.064012] [<ffffffff81003587>] do_softirq+0x45/0x82
[ 452.064012] [<ffffffff81034667>] irq_exit+0x42/0x9c
[ 452.064012] [<ffffffff8125e146>] do_IRQ+0x8e/0xa5
[ 452.064012] [<ffffffff8125676e>] common_interrupt+0x6e/0x6e
[ 452.064012] <EOI> [<ffffffff810b82a1>] ? kfree+0x8a/0xa3
[ 452.064012] [<ffffffffa01b2cc2>] ? l2tp_xmit_skb+0x27a/0x4ac [l2tp_core]
[ 452.064012] [<ffffffffa01b2c25>] ? l2tp_xmit_skb+0x1dd/0x4ac [l2tp_core]
[ 452.064012] [<ffffffffa01c2d36>] pppol2tp_sendmsg+0x15e/0x19c [l2tp_ppp]
[ 452.064012] [<ffffffff811c7872>] __sock_sendmsg_nosec+0x22/0x24
[ 452.064012] [<ffffffff811c83bd>] sock_sendmsg+0xa1/0xb6
[ 452.064012] [<ffffffff81254e88>] ? __schedule+0x5c1/0x616
[ 452.064012] [<ffffffff8103c7c6>] ? __dequeue_signal+0xb7/0x10c
[ 452.064012] [<ffffffff810bbd21>] ? fget_light+0x75/0x89
[ 452.064012] [<ffffffff811c8444>] ? sockfd_lookup_light+0x20/0x56
[ 452.064012] [<ffffffff811c9b34>] sys_sendto+0x10c/0x13b
[ 452.064012] [<ffffffff8125cac2>] system_call_fastpath+0x16/0x1b
Reported-by: François Cachereul <f.cachereul@alphalink.fr>
Tested-by: François Cachereul <f.cachereul@alphalink.fr>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 5ebee2d..8c46b27 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -353,7 +353,9 @@
goto error_put_sess_tun;
}
+ local_bh_disable();
l2tp_xmit_skb(session, skb, session->hdr_len);
+ local_bh_enable();
sock_put(ps->tunnel_sock);
sock_put(sk);
@@ -422,7 +424,9 @@
skb->data[0] = ppph[0];
skb->data[1] = ppph[1];
+ local_bh_disable();
l2tp_xmit_skb(session, skb, session->hdr_len);
+ local_bh_enable();
sock_put(sk_tun);
sock_put(sk);