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[PATCH] Don't attach callback to a going-away netlink socket [message #12043] Mon, 16 April 2007 11:34 Go to previous message
xemul is currently offline  xemul
Messages: 248
Registered: November 2005
Senior Member
From: Denis Lunev <den@openvz.org>

There is a race between netlink_dump_start() and netlink_release()
that can lead to the situation when a netlink socket with non-zero
callback is freed.

--- a/net/netlink/af_netlink.c 2004-10-25 12:12:23.000000000 +0400
+++ b/net/netlink/af_netlink.c 2004-10-28 16:26:12.000000000 +0400
@@ -255,6 +255,7 @@ static int netlink_release(struct socket
return 0;

netlink_remove(sk);
+ sock_orphan(sk);
nlk = nlk_sk(sk);

spin_lock(&nlk->cb_lock);
@@ -269,7 +270,6 @@ static int netlink_release(struct socket
/* OK. Socket is unlinked, and, therefore,
no new packets will arrive */

- sock_orphan(sk);
sock->sk = NULL;
wake_up_interruptible_all(&nlk->wait);

@@ -942,9 +942,9 @@ int netlink_dump_start(struct sock *ssk,
return -ECONNREFUSED;
}
nlk = nlk_sk(sk);
- /* A dump is in progress... */
+ /* A dump or destruction is in progress... */
spin_lock(&nlk->cb_lock);
- if (nlk->cb) {
+ if (nlk->cb || sock_flag(sk, SOCK_DEAD)) {
spin_unlock(&nlk->cb_lock);
netlink_destroy_callback(cb);
sock_put(sk);
 
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