From eefc1b1d105ee4d2ce907833ce675f1e9599b5e3 Mon Sep 17 00:00:00 2001 From: Marcelo Ricardo Leitner Date: Sat, 23 Jul 2016 00:32:48 -0300 Subject: sctp: fix BH handling on socket backlog Now that the backlog processing is called with BH enabled, we have to disable BH before taking the socket lock via bh_lock_sock() otherwise it may dead lock: sctp_backlog_rcv() bh_lock_sock(sk); if (sock_owned_by_user(sk)) { if (sk_add_backlog(sk, skb, sk->sk_rcvbuf)) sctp_chunk_free(chunk); else backloged = 1; } else sctp_inq_push(inqueue, chunk); bh_unlock_sock(sk); while sctp_inq_push() was disabling/enabling BH, but enabling BH triggers pending softirq, which then may try to re-lock the socket in sctp_rcv(). [ 219.187215] [ 219.187217] [] _raw_spin_lock+0x20/0x30 [ 219.187223] [] sctp_rcv+0x48c/0xba0 [sctp] [ 219.187225] [] ? nf_iterate+0x62/0x80 [ 219.187226] [] ip_local_deliver_finish+0x94/0x1e0 [ 219.187228] [] ip_local_deliver+0x6f/0xf0 [ 219.187229] [] ? ip_rcv_finish+0x3b0/0x3b0 [ 219.187230] [] ip_rcv_finish+0xd8/0x3b0 [ 219.187232] [] ip_rcv+0x282/0x3a0 [ 219.187233] [] ? update_curr+0x66/0x180 [ 219.187235] [] __netif_receive_skb_core+0x524/0xa90 [ 219.187236] [] ? update_cfs_shares+0x30/0xf0 [ 219.187237] [] ? __enqueue_entity+0x6c/0x70 [ 219.187239] [] ? enqueue_entity+0x204/0xdf0 [ 219.187240] [] __netif_receive_skb+0x18/0x60 [ 219.187242] [] process_backlog+0x9e/0x140 [ 219.187243] [] net_rx_action+0x22c/0x370 [ 219.187245] [] __do_softirq+0x112/0x2e7 [ 219.187247] [] do_softirq_own_stack+0x1c/0x30 [ 219.187247] [ 219.187248] [] do_softirq.part.14+0x38/0x40 [ 219.187249] [] __local_bh_enable_ip+0x7d/0x80 [ 219.187254] [] sctp_inq_push+0x68/0x80 [sctp] [ 219.187258] [] sctp_backlog_rcv+0x151/0x1c0 [sctp] [ 219.187260] [] __release_sock+0x87/0xf0 [ 219.187261] [] release_sock+0x30/0xa0 [ 219.187265] [] sctp_accept+0x17d/0x210 [sctp] [ 219.187266] [] ? prepare_to_wait_event+0xf0/0xf0 [ 219.187268] [] inet_accept+0x3c/0x130 [ 219.187269] [] SYSC_accept4+0x103/0x210 [ 219.187271] [] ? _raw_spin_unlock_bh+0x1a/0x20 [ 219.187272] [] ? release_sock+0x8c/0xa0 [ 219.187276] [] ? sctp_inet_listen+0x62/0x1b0 [sctp] [ 219.187277] [] SyS_accept+0x10/0x20 Fixes: 860fbbc343bf ("sctp: prepare for socket backlog behavior change") Cc: Eric Dumazet Signed-off-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- net/sctp/input.c | 2 ++ net/sctp/inqueue.c | 2 -- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/sctp/input.c b/net/sctp/input.c index 30d72f7707b6..c182db7d691f 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -321,6 +321,7 @@ int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) */ sk = rcvr->sk; + local_bh_disable(); bh_lock_sock(sk); if (sock_owned_by_user(sk)) { @@ -332,6 +333,7 @@ int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb) sctp_inq_push(inqueue, chunk); bh_unlock_sock(sk); + local_bh_enable(); /* If the chunk was backloged again, don't drop refs */ if (backloged) diff --git a/net/sctp/inqueue.c b/net/sctp/inqueue.c index 942770675f4c..c30ddb0f3190 100644 --- a/net/sctp/inqueue.c +++ b/net/sctp/inqueue.c @@ -89,12 +89,10 @@ void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk) * Eventually, we should clean up inqueue to not rely * on the BH related data structures. */ - local_bh_disable(); list_add_tail(&chunk->list, &q->in_chunk_list); if (chunk->asoc) chunk->asoc->stats.ipackets++; q->immediate.func(&q->immediate); - local_bh_enable(); } /* Peek at the next chunk on the inqeue. */ -- cgit v1.2.1