kernel.git/net/sctp/sm_sideeffect.c, branch linux-4.1.y

sctp: Prevent soft lockup when sctp_accept() is called during a timeout event

2016-01-31T19:23:38Z

[ Upstream commit 635682a14427d241bab7bbdeebb48a7d7b91638e ] A case can occur when sctp_accept() is called by the user during a heartbeat timeout event after the 4-way handshake. Since sctp_assoc_migrate() changes both assoc->base.sk and assoc->ep, the bh_sock_lock in sctp_generate_heartbeat_event() will be taken with the listening socket but released with the new association socket. The result is a deadlock on any future attempts to take the listening socket lock. Note that this race can occur with other SCTP timeouts that take the bh_lock_sock() in the event sctp_accept() is called. BUG: soft lockup - CPU#9 stuck for 67s! [swapper:0] ... RIP: 0010:[] [] _spin_lock+0x1e/0x30 RSP: 0018:ffff880028323b20 EFLAGS: 00000206 RAX: 0000000000000002 RBX: ffff880028323b20 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff880028323be0 RDI: ffff8804632c4b48 RBP: ffffffff8100bb93 R08: 0000000000000000 R09: 0000000000000000 R10: ffff880610662280 R11: 0000000000000100 R12: ffff880028323aa0 R13: ffff8804383c3880 R14: ffff880028323a90 R15: ffffffff81534225 FS: 0000000000000000(0000) GS:ffff880028320000(0000) knlGS:0000000000000000 CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b CR2: 00000000006df528 CR3: 0000000001a85000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process swapper (pid: 0, threadinfo ffff880616b70000, task ffff880616b6cab0) Stack: ffff880028323c40 ffffffffa01c2582 ffff880614cfb020 0000000000000000 0100000000000000 00000014383a6c44 ffff8804383c3880 ffff880614e93c00 ffff880614e93c00 0000000000000000 ffff8804632c4b00 ffff8804383c38b8 Call Trace: [] ? sctp_rcv+0x492/0xa10 [sctp] [] ? nf_iterate+0x69/0xb0 [] ? ip_local_deliver_finish+0x0/0x2d0 [] ? nf_hook_slow+0x76/0x120 [] ? ip_local_deliver_finish+0x0/0x2d0 [] ? ip_local_deliver_finish+0xdd/0x2d0 [] ? ip_local_deliver+0x98/0xa0 [] ? ip_rcv_finish+0x12d/0x440 [] ? ip_rcv+0x275/0x350 [] ? __netif_receive_skb+0x4ab/0x750 ... With lockdep debugging: ===================================== [ BUG: bad unlock balance detected! ] ------------------------------------- CslRx/12087 is trying to release lock (slock-AF_INET) at: [] sctp_generate_timeout_event+0x40/0xe0 [sctp] but there are no more locks to release! other info that might help us debug this: 2 locks held by CslRx/12087: #0: (&asoc->timers[i]){+.-...}, at: [] run_timer_softirq+0x16f/0x3e0 #1: (slock-AF_INET){+.-...}, at: [] sctp_generate_timeout_event+0x23/0xe0 [sctp] Ensure the socket taken is also the same one that is released by saving a copy of the socket before entering the timeout event critical section. Signed-off-by: Karl Heiss Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: sctp: Don't transition to PF state when transport has exhausted 'Path.Max.Retrans'.

2014-04-28T03:41:14Z

Don't transition to the PF state on every strike after 'Path.Max.Retrans'. Per draft-ietf-tsvwg-sctp-failover-03 Section 5.1.6: Additional (PMR - PFMR) consecutive timeouts on a PF destination confirm the path failure, upon which the destination transitions to the Inactive state. As described in [RFC4960], the sender (i) SHOULD notify ULP about this state transition, and (ii) transmit heartbeats to the Inactive destination at a lower frequency as described in Section 8.3 of [RFC4960]. This also prevents sending SCTP_ADDR_UNREACHABLE to the user as the state bounces between SCTP_INACTIVE and SCTP_PF for each subsequent strike. Signed-off-by: Karl Heiss Acked-by: Vlad Yasevich Signed-off-by: David S. Miller

net: sctp: Potentially-Failed state should not be reached from unconfirmed state

2014-02-20T18:24:56Z

In current implementation it is possible to reach PF state from unconfirmed. We can interpret sctp-failover-02 in a way that PF state is meant to be reached only from active state, in the end, this is when entering PF state makes sense. Here are few quotes from sctp-failover-02, but regardless of these, same understanding can be reached from whole section 5: Section 5.1, quickfailover guide: "The PF state is an intermediate state between Active and Failed states." "Each time the T3-rtx timer expires on an active or idle destination, the error counter of that destination address will be incremented. When the value in the error counter exceeds PFMR, the endpoint should mark the destination transport address as PF." There are several concrete reasons for such interpretation. For start, rfc4960 does not take into concern quickfailover algorithm. Therefore, quickfailover must comply to 4960. Point where this compliance can be argued is following behavior: When PF is entered, association overall error counter is incremented for each missed HB. This is contradictory to rfc4960, as address, while in unconfirmed state, is subjected to probing, and while it is probed, it should not increment association overall error counter. This has as a consequence that we might end up in situation in which we drop association due path failure on unconfirmed address, in case we have wrong configuration in a way: Association.Max.Retrans == Path.Max.Retrans. Another reason is that entering PF from unconfirmed will cause a loss of address confirmed event when address is once (if) confirmed. This is fine from failover guide point of view, but it is not consistent with behavior preceding failover implementation and recommendation from 4960: 5.4. Path Verification Whenever a path is confirmed, an indication MAY be given to the upper layer. Signed-off-by: Matija Glavinic Pecotic Acked-by: Vlad Yasevich Signed-off-by: David S. Miller

sctp: remove macros sctp_bh_[un]lock_sock

2014-01-22T02:41:36Z

Redefined bh_[un]lock_sock to sctp_bh[un]lock_sock for user space friendly code which we haven't use in years, so removing them. Signed-off-by: Wang Weidong Signed-off-by: David S. Miller

sctp: fix checkpatch errors with space required or prohibited

2013-12-26T18:47:47Z

fix checkpatch errors while the space is required or prohibited to the "=,()++..." Acked-by: Neil Horman Signed-off-by: Wang Weidong Signed-off-by: David S. Miller

sctp: remove casting from function calls through ops structure

2013-12-22T23:04:28Z

remove the unnecessary cast. Signed-off-by: Wang Weidong Acked-by: Neil Horman Signed-off-by: David S. Miller

sctp: Fix FSF address in file headers

2013-12-06T17:37:56Z

Several files refer to an old address for the Free Software Foundation in the file header comment. Resolve by replacing the address with the URL so that we do not have to keep updating the header comments anytime the address changes. CC: Vlad Yasevich CC: Neil Horman Signed-off-by: Jeff Kirsher Signed-off-by: David S. Miller

net: sctp: do not trigger BUG_ON in sctp_cmd_delete_tcb

2013-11-04T05:46:44Z

Introduced in f9e42b853523 ("net: sctp: sideeffect: throw BUG if primary_path is NULL"), we intended to find a buggy assoc that's part of the assoc hash table with a primary_path that is NULL. However, we better remove the BUG_ON for now and find a more suitable place to assert for these things as Mark reports that this also triggers the bug when duplication cookie processing happens, and the assoc is not part of the hash table (so all good in this case). Such a situation can for example easily be reproduced by: tc qdisc add dev eth0 root handle 1: prio bands 2 priomap 1 1 1 1 1 1 tc qdisc add dev eth0 parent 1:2 handle 20: netem loss 20% tc filter add dev eth0 protocol ip parent 1: prio 2 u32 match ip \ protocol 132 0xff match u8 0x0b 0xff at 32 flowid 1:2 This drops 20% of COOKIE-ACK packets. After some follow-up discussion with Vlad we came to the conclusion that for now we should still better remove this BUG_ON() assertion, and come up with two follow-ups later on, that is, i) find a more suitable place for this assertion, and possibly ii) have a special allocator/initializer for such kind of temporary assocs. Reported-by: Mark Thomas Signed-off-by: Vlad Yasevich Signed-off-by: Daniel Borkmann Acked-by: Neil Horman Signed-off-by: David S. Miller

net: sctp: trivial: update bug report in header comment

2013-08-09T18:33:02Z

With the restructuring of the lksctp.org site, we only allow bug reports through the SCTP mailing list linux-sctp@vger.kernel.org, not via SF, as SF is only used for web hosting and nothing more. While at it, also remove the obvious statement that bugs will be fixed and incooperated into the kernel. Signed-off-by: Daniel Borkmann Acked-by: Vlad Yasevich Signed-off-by: David S. Miller

net: sctp: trivial: update mailing list address

2013-07-25T00:53:38Z

The SCTP mailing list address to send patches or questions to is linux-sctp@vger.kernel.org and not lksctp-developers@lists.sourceforge.net anymore. Therefore, update all occurences. Signed-off-by: Daniel Borkmann Acked-by: Neil Horman Acked-by: Vlad Yasevich Signed-off-by: David S. Miller