| Message ID | a19b6088999a30defbfce748bc178935156a18a3.1469244527.git.marcelo.leitner@gmail.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Date: Sat, 23 Jul 2016 00:32:48 -0300 > 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: ... > Fixes: 860fbbc343bf ("sctp: prepare for socket backlog behavior change") > Cc: Eric Dumazet <eric.dumazet@gmail.com> > Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Applied and queued up for -stable, thanks.
diff --git a/net/sctp/input.c b/net/sctp/input.c index 30d72f7707b6df5b41679bbfc5e595d5a11130ea..c182db7d691ff44a52923fb36c9170e49c141c04 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -328,6 +328,7 @@ 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)) { @@ -339,6 +340,7 @@ 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 942770675f4cc0efc9686f4e4038450f060f34ae..c30ddb0f31907f57c5ce85b00dbe04260ca1cb2e 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. */
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] <IRQ> [ 219.187217] [<ffffffff817ca3e0>] _raw_spin_lock+0x20/0x30 [ 219.187223] [<ffffffffa041888c>] sctp_rcv+0x48c/0xba0 [sctp] [ 219.187225] [<ffffffff816e7db2>] ? nf_iterate+0x62/0x80 [ 219.187226] [<ffffffff816f1b14>] ip_local_deliver_finish+0x94/0x1e0 [ 219.187228] [<ffffffff816f1e1f>] ip_local_deliver+0x6f/0xf0 [ 219.187229] [<ffffffff816f1a80>] ? ip_rcv_finish+0x3b0/0x3b0 [ 219.187230] [<ffffffff816f17a8>] ip_rcv_finish+0xd8/0x3b0 [ 219.187232] [<ffffffff816f2122>] ip_rcv+0x282/0x3a0 [ 219.187233] [<ffffffff810d8bb6>] ? update_curr+0x66/0x180 [ 219.187235] [<ffffffff816abac4>] __netif_receive_skb_core+0x524/0xa90 [ 219.187236] [<ffffffff810d8e00>] ? update_cfs_shares+0x30/0xf0 [ 219.187237] [<ffffffff810d557c>] ? __enqueue_entity+0x6c/0x70 [ 219.187239] [<ffffffff810dc454>] ? enqueue_entity+0x204/0xdf0 [ 219.187240] [<ffffffff816ac048>] __netif_receive_skb+0x18/0x60 [ 219.187242] [<ffffffff816ad1ce>] process_backlog+0x9e/0x140 [ 219.187243] [<ffffffff816ac8ec>] net_rx_action+0x22c/0x370 [ 219.187245] [<ffffffff817cd352>] __do_softirq+0x112/0x2e7 [ 219.187247] [<ffffffff817cc3bc>] do_softirq_own_stack+0x1c/0x30 [ 219.187247] <EOI> [ 219.187248] [<ffffffff810aa1c8>] do_softirq.part.14+0x38/0x40 [ 219.187249] [<ffffffff810aa24d>] __local_bh_enable_ip+0x7d/0x80 [ 219.187254] [<ffffffffa0408428>] sctp_inq_push+0x68/0x80 [sctp] [ 219.187258] [<ffffffffa04190f1>] sctp_backlog_rcv+0x151/0x1c0 [sctp] [ 219.187260] [<ffffffff81692b07>] __release_sock+0x87/0xf0 [ 219.187261] [<ffffffff81692ba0>] release_sock+0x30/0xa0 [ 219.187265] [<ffffffffa040e46d>] sctp_accept+0x17d/0x210 [sctp] [ 219.187266] [<ffffffff810e7510>] ? prepare_to_wait_event+0xf0/0xf0 [ 219.187268] [<ffffffff8172d52c>] inet_accept+0x3c/0x130 [ 219.187269] [<ffffffff8168d7a3>] SYSC_accept4+0x103/0x210 [ 219.187271] [<ffffffff817ca2ba>] ? _raw_spin_unlock_bh+0x1a/0x20 [ 219.187272] [<ffffffff81692bfc>] ? release_sock+0x8c/0xa0 [ 219.187276] [<ffffffffa0413e22>] ? sctp_inet_listen+0x62/0x1b0 [sctp] [ 219.187277] [<ffffffff8168f2d0>] SyS_accept+0x10/0x20 Fixes: 860fbbc343bf ("sctp: prepare for socket backlog behavior change") Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> --- net/sctp/input.c | 2 ++ net/sctp/inqueue.c | 2 -- 2 files changed, 2 insertions(+), 2 deletions(-)