| From 01bfe5e8e428b475982a98a46cca5755726f3f7f Mon Sep 17 00:00:00 2001 |
| From: Xin Long <lucien.xin@gmail.com> |
| Date: Mon, 3 May 2021 05:11:41 +0800 |
| Subject: Revert "net/sctp: fix race condition in sctp_destroy_sock" |
| |
| 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> |
| --- |
| net/sctp/socket.c | 13 ++++++++----- |
| 1 file changed, 8 insertions(+), 5 deletions(-) |
| |
| --- a/net/sctp/socket.c |
| +++ b/net/sctp/socket.c |
| @@ -1520,9 +1520,11 @@ static void sctp_close(struct sock *sk, |
| |
| /* 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. |
| @@ -1531,7 +1533,7 @@ static void sctp_close(struct sock *sk, |
| sk_common_release(sk); |
| |
| bh_unlock_sock(sk); |
| - local_bh_enable(); |
| + spin_unlock_bh(&net->sctp.addr_wq_lock); |
| |
| sock_put(sk); |
| |
| @@ -4991,6 +4993,9 @@ static int sctp_init_sock(struct sock *s |
| 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, |
| @@ -5025,9 +5030,7 @@ static void sctp_destroy_sock(struct soc |
| |
| 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(); |