linux/net/sctp
Vegard Nossum 54236ab09e net/sctp: always initialise sctp_ht_iter::start_fail
sctp_transport_seq_start() does not currently clear iter->start_fail on
success, but relies on it being zero when it is allocated (by
seq_open_net()).

This can be a problem in the following sequence:

    open() // allocates iter (and implicitly sets iter->start_fail = 0)
    read()
     - iter->start() // fails and sets iter->start_fail = 1
     - iter->stop() // doesn't call sctp_transport_walk_stop() (correct)
    read() again
     - iter->start() // succeeds, but doesn't change iter->start_fail
     - iter->stop() // doesn't call sctp_transport_walk_stop() (wrong)

We should initialize sctp_ht_iter::start_fail to zero if ->start()
succeeds, otherwise it's possible that we leave an old value of 1 there,
which will cause ->stop() to not call sctp_transport_walk_stop(), which
causes all sorts of problems like not calling rcu_read_unlock() (and
preempt_enable()), eventually leading to more warnings like this:

    BUG: sleeping function called from invalid context at mm/slab.h:388
    in_atomic(): 0, irqs_disabled(): 0, pid: 16551, name: trinity-c2
    Preemption disabled at:[<ffffffff819bceb6>] rhashtable_walk_start+0x46/0x150

     [<ffffffff81149abb>] preempt_count_add+0x1fb/0x280
     [<ffffffff83295892>] _raw_spin_lock+0x12/0x40
     [<ffffffff819bceb6>] rhashtable_walk_start+0x46/0x150
     [<ffffffff82ec665f>] sctp_transport_walk_start+0x2f/0x60
     [<ffffffff82edda1d>] sctp_transport_seq_start+0x4d/0x150
     [<ffffffff81439e50>] traverse+0x170/0x850
     [<ffffffff8143aeec>] seq_read+0x7cc/0x1180
     [<ffffffff814f996c>] proc_reg_read+0xbc/0x180
     [<ffffffff813d0384>] do_loop_readv_writev+0x134/0x210
     [<ffffffff813d2a95>] do_readv_writev+0x565/0x660
     [<ffffffff813d6857>] vfs_readv+0x67/0xa0
     [<ffffffff813d6c16>] do_preadv+0x126/0x170
     [<ffffffff813d710c>] SyS_preadv+0xc/0x10
     [<ffffffff8100334c>] do_syscall_64+0x19c/0x410
     [<ffffffff83296225>] return_from_SYSCALL_64+0x0/0x6a
     [<ffffffffffffffff>] 0xffffffffffffffff

Notice that this is a subtly different stacktrace from the one in commit
5fc382d875 ("net/sctp: terminate rhashtable walk correctly").

Cc: Xin Long <lucien.xin@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-By: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-13 15:10:16 -07:00
..
associola.c sctp: add SCTP_PR_SUPPORTED on sctp sockopt 2016-07-11 13:25:38 -07:00
auth.c sctp: Use shash 2016-01-27 20:36:15 +08:00
bind_addr.c sctp: fix copying more bytes than expected in sctp_add_bind_addr 2016-03-08 15:04:08 -05:00
chunk.c sctp: implement prsctp PRIO policy 2016-07-11 13:25:39 -07:00
debug.c sctp: Fix FSF address in file headers 2013-12-06 12:37:56 -05:00
endpointola.c sctp: add SCTP_PR_SUPPORTED on sctp sockopt 2016-07-11 13:25:38 -07:00
input.c sctp: fix BH handling on socket backlog 2016-07-25 11:22:22 -07:00
inqueue.c sctp: fix BH handling on socket backlog 2016-07-25 11:22:22 -07:00
ipv6.c sctp: use inet_recvmsg to support sctp RFS well 2016-07-25 10:56:28 -07:00
Kconfig sctp: add the sctp_diag.c file 2016-04-15 17:29:36 -04:00
Makefile sctp: Add GSO support 2016-06-03 19:37:21 -04:00
objcnt.c sctp: fix checkpatch errors with (foo*)|foo * bar|foo* bar 2013-12-26 13:47:47 -05:00
offload.c sctp: fix GSO for IPv6 2016-07-16 22:02:09 -07:00
output.c sctp: fix the issue sctp requeue auth chunk incorrectly 2016-07-30 22:06:22 -07:00
outqueue.c sctp: implement prsctp PRIO policy 2016-07-11 13:25:39 -07:00
primitive.c sctp: Fix FSF address in file headers 2013-12-06 12:37:56 -05:00
probe.c net: sctp: Convert log timestamps to be y2038 safe 2016-03-01 17:18:44 -05:00
proc.c net/sctp: always initialise sctp_ht_iter::start_fail 2016-08-13 15:10:16 -07:00
protocol.c sctp: use inet_recvmsg to support sctp RFS well 2016-07-25 10:56:28 -07:00
sctp_diag.c sctp_diag: Respect ss adding TCPF_CLOSE to idiag_states 2016-08-08 12:51:58 -07:00
sm_make_chunk.c sctp: avoid identifying address family many times for a chunk 2016-07-13 18:10:14 -07:00
sm_sideeffect.c sctp: sctp should change socket state when shutdown is received 2016-06-10 23:21:23 -07:00
sm_statefuns.c sctp: only check for ECN if peer is using it 2016-07-13 18:10:14 -07:00
sm_statetable.c sctp: fix checkpatch errors with indent 2013-12-26 13:47:48 -05:00
socket.c sctp: allow receiving msg when TCP-style sk is in CLOSED state 2016-07-30 22:06:22 -07:00
ssnmap.c sctp: Fix FSF address in file headers 2013-12-06 12:37:56 -05:00
sysctl.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-01-11 23:55:43 -05:00
transport.c sctp: avoid refreshing heartbeat timer too often 2016-04-10 22:22:34 -04:00
tsnmap.c sctp: Fix FSF address in file headers 2013-12-06 12:37:56 -05:00
ulpevent.c sctp: use event->chunk when it's valid 2016-08-08 14:31:23 -07:00
ulpqueue.c sctp: allow delivering notifications after receiving SHUTDOWN 2016-07-30 22:06:22 -07:00