[PATCH net-next] sctp: fix recursive locking warning in sctp_do_peeloff
From: Xin Long <lucien.xin@gmail.com>
Date: 2017-06-10 06:57:05
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 <redacted> Signed-off-by: Xin Long <lucien.xin@gmail.com> --- net/sctp/socket.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 5f58dd0..32d5495 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c@@ -1494,7 +1494,7 @@ static void sctp_close(struct sock *sk, long timeout) 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;
@@ -1544,7 +1544,7 @@ static void sctp_close(struct sock *sk, long timeout) * 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.
--
2.1.0