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authorXin Long <lucien.xin@gmail.com>2021-05-03 05:11:41 +0800
committerDavid S. Miller <davem@davemloft.net>2021-05-03 13:36:21 -0700
commit01bfe5e8e428b475982a98a46cca5755726f3f7f (patch)
tree493ce8d5208472d790b499e710c44a7704cbe256 /net
parent2e9f60932a2c19e8a11b4a69d419f107024b05a0 (diff)
Revert "net/sctp: fix race condition in sctp_destroy_sock"
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>
Diffstat (limited to 'net')
-rw-r--r--net/sctp/socket.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index b7b90135c36a..76a388b5021c 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1520,9 +1520,11 @@ 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.
@@ -1531,7 +1533,7 @@ 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);
@@ -4991,6 +4993,9 @@ 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,
@@ -5025,9 +5030,7 @@ 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();