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authorVegard Nossum <vegard.nossum@oracle.com>2016-08-12 09:50:51 +0200
committerDavid S. Miller <davem@davemloft.net>2016-08-13 15:10:16 -0700
commit54236ab09e9696a27baaae693c288920a26e8588 (patch)
tree3142a23b93e3505f7398247b26c65f7f6bf22f18 /net/sctp
parent5ba092efc7ddff040777ae7162f1d195f513571b (diff)
downloadlinux-54236ab09e9696a27baaae693c288920a26e8588.tar.bz2
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>
Diffstat (limited to 'net/sctp')
-rw-r--r--net/sctp/proc.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/net/sctp/proc.c b/net/sctp/proc.c
index 4cb5aedfe3ee..ef8ba77a5bea 100644
--- a/net/sctp/proc.c
+++ b/net/sctp/proc.c
@@ -293,6 +293,7 @@ static void *sctp_transport_seq_start(struct seq_file *seq, loff_t *pos)
return ERR_PTR(err);
}
+ iter->start_fail = 0;
return sctp_transport_get_idx(seq_file_net(seq), &iter->hti, *pos);
}