This is a note to let you know that I've just added the patch titled
sctp: fix recursive locking warning in sctp_do_peeloff
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: sctp-fix-recursive-locking-warning-in-sctp_do_peeloff.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Mon Apr 9 17:09:24 CEST 2018
From: Xin Long lucien.xin@gmail.com Date: Sat, 10 Jun 2017 14:56:56 +0800 Subject: sctp: fix recursive locking warning in sctp_do_peeloff
From: Xin Long lucien.xin@gmail.com
[ Upstream commit 6dfe4b97e08ec3d1a593fdaca099f0ef0a3a19e6 ]
Dmitry got the following recursive locking report while running syzkaller fuzzer, the Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x2ee/0x3ef lib/dump_stack.c:52 print_deadlock_bug kernel/locking/lockdep.c:1729 [inline] check_deadlock kernel/locking/lockdep.c:1773 [inline] validate_chain kernel/locking/lockdep.c:2251 [inline] __lock_acquire+0xef2/0x3430 kernel/locking/lockdep.c:3340 lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755 lock_sock_nested+0xcb/0x120 net/core/sock.c:2536 lock_sock include/net/sock.h:1460 [inline] sctp_close+0xcd/0x9d0 net/sctp/socket.c:1497 inet_release+0xed/0x1c0 net/ipv4/af_inet.c:425 inet6_release+0x50/0x70 net/ipv6/af_inet6.c:432 sock_release+0x8d/0x1e0 net/socket.c:597 __sock_create+0x38b/0x870 net/socket.c:1226 sock_create+0x7f/0xa0 net/socket.c:1237 sctp_do_peeloff+0x1a2/0x440 net/sctp/socket.c:4879 sctp_getsockopt_peeloff net/sctp/socket.c:4914 [inline] sctp_getsockopt+0x111a/0x67e0 net/sctp/socket.c:6628 sock_common_getsockopt+0x95/0xd0 net/core/sock.c:2690 SYSC_getsockopt net/socket.c:1817 [inline] SyS_getsockopt+0x240/0x380 net/socket.c:1799 entry_SYSCALL_64_fastpath+0x1f/0xc2
This warning is caused by the lock held by sctp_getsockopt() is on one socket, while the other lock that sctp_close() is getting later is on the newly created (which failed) socket during peeloff operation.
This patch is to avoid this warning by use lock_sock with subclass SINGLE_DEPTH_NESTING as Wang Cong and Marcelo's suggestion.
Reported-by: Dmitry Vyukov dvyukov@google.com Suggested-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Suggested-by: Cong Wang xiyou.wangcong@gmail.com Signed-off-by: Xin Long lucien.xin@gmail.com Acked-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sctp/socket.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -1519,7 +1519,7 @@ static void sctp_close(struct sock *sk,
pr_debug("%s: sk:%p, timeout:%ld\n", __func__, sk, timeout);
- lock_sock(sk); + lock_sock_nested(sk, SINGLE_DEPTH_NESTING); sk->sk_shutdown = SHUTDOWN_MASK; sk->sk_state = SCTP_SS_CLOSING;
@@ -1569,7 +1569,7 @@ static void sctp_close(struct sock *sk, * held and that should be grabbed before socket lock. */ spin_lock_bh(&net->sctp.addr_wq_lock); - bh_lock_sock(sk); + bh_lock_sock_nested(sk);
/* Hold the sock, since sk_common_release() will put sock_put() * and we have just a little more cleanup.
Patches currently in stable-queue which might be from lucien.xin@gmail.com are
queue-4.9/sctp-fix-recursive-locking-warning-in-sctp_do_peeloff.patch