This is a note to let you know that I've just added the patch titled net/sctp: always initialise sctp_ht_iter::start_fail to the 4.7-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-sctp-always-initialise-sctp_ht_iter-start_fail.patch and it can be found in the queue-4.7 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Sep 21 10:05:18 CEST 2016 From: Vegard Nossum <vegard.nossum@xxxxxxxxxx> Date: Fri, 12 Aug 2016 09:50:51 +0200 Subject: net/sctp: always initialise sctp_ht_iter::start_fail From: Vegard Nossum <vegard.nossum@xxxxxxxxxx> [ Upstream commit 54236ab09e9696a27baaae693c288920a26e8588 ] 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@xxxxxxxxx> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> Cc: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx> Acked-By: Neil Horman <nhorman@xxxxxxxxxxxxx> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/sctp/proc.c | 1 + 1 file changed, 1 insertion(+) --- a/net/sctp/proc.c +++ b/net/sctp/proc.c @@ -293,6 +293,7 @@ static void *sctp_transport_seq_start(st return ERR_PTR(err); } + iter->start_fail = 0; return sctp_transport_get_idx(seq_file_net(seq), &iter->hti, *pos); } Patches currently in stable-queue which might be from vegard.nossum@xxxxxxxxxx are queue-4.7/net-sctp-always-initialise-sctp_ht_iter-start_fail.patch queue-4.7/net-irda-handle-iriap_register_lsap-allocation-failure.patch queue-4.7/tipc-fix-null-pointer-dereference-in-shutdown.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html