From: Xin Long lucien.xin@gmail.com
commit 01bfe5e8e428b475982a98a46cca5755726f3f7f upstream.
This reverts commit b166a20b07382b8bc1dcee2a448715c9c2c81b5b.
This one has to be reverted as it introduced a dead lock, as syzbot reported:
CPU0 CPU1 ---- ---- lock(&net->sctp.addr_wq_lock); lock(slock-AF_INET6); lock(&net->sctp.addr_wq_lock); lock(slock-AF_INET6);
CPU0 is the thread of sctp_addr_wq_timeout_handler(), and CPU1 is that of sctp_close().
The original issue this commit fixed will be fixed in the next patch.
Reported-by: syzbot+959223586843e69a2674@syzkaller.appspotmail.com Signed-off-by: Xin Long lucien.xin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- net/sctp/socket.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/net/sctp/socket.c b/net/sctp/socket.c index addfc8feaef57..733c3f4480087 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -1571,9 +1571,11 @@ static void sctp_close(struct sock *sk, long timeout)
/* Supposedly, no process has access to the socket, but * the net layers still may. + * Also, sctp_destroy_sock() needs to be called with addr_wq_lock + * held and that should be grabbed before socket lock. */ - local_bh_disable(); - bh_lock_sock(sk); + spin_lock_bh(&net->sctp.addr_wq_lock); + bh_lock_sock_nested(sk);
/* Hold the sock, since sk_common_release() will put sock_put() * and we have just a little more cleanup. @@ -1582,7 +1584,7 @@ static void sctp_close(struct sock *sk, long timeout) sk_common_release(sk);
bh_unlock_sock(sk); - local_bh_enable(); + spin_unlock_bh(&net->sctp.addr_wq_lock);
sock_put(sk);
@@ -4777,6 +4779,9 @@ static int sctp_init_sock(struct sock *sk) sk_sockets_allocated_inc(sk); sock_prot_inuse_add(net, sk->sk_prot, 1);
+ /* Nothing can fail after this block, otherwise + * sctp_destroy_sock() will be called without addr_wq_lock held + */ if (net->sctp.default_auto_asconf) { spin_lock(&sock_net(sk)->sctp.addr_wq_lock); list_add_tail(&sp->auto_asconf_list, @@ -4811,9 +4816,7 @@ static void sctp_destroy_sock(struct sock *sk)
if (sp->do_auto_asconf) { sp->do_auto_asconf = 0; - spin_lock_bh(&sock_net(sk)->sctp.addr_wq_lock); list_del(&sp->auto_asconf_list); - spin_unlock_bh(&sock_net(sk)->sctp.addr_wq_lock); } sctp_endpoint_free(sp->ep); local_bh_disable();