Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ac57b3a9ce280763296f99e32187a0b4384d9389
Commit: ac57b3a9ce280763296f99e32187a0b4384d9389
Parent: bfb6709d0b239af5e3ce5859aae926e1b79ba84b
Author: Denis Lunev <[EMAIL PROTECTED]>
AuthorDate: Wed Apr 18 17:05:58 2007 -0700
Committer: David S. Miller <[EMAIL PROTECTED]>
CommitDate: Wed Apr 18 17:05:58 2007 -0700
[NETLINK]: Don't attach callback to a going-away netlink socket
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.
Here it is:
CPU1: CPU2
netlink_release(): netlink_dump_start():
sk = netlink_lookup(); /* OK */
netlink_remove();
spin_lock(&nlk->cb_lock);
if (nlk->cb) { /* false */
...
}
spin_unlock(&nlk->cb_lock);
spin_lock(&nlk->cb_lock);
if (nlk->cb) { /* false */
...
}
nlk->cb = cb;
spin_unlock(&nlk->cb_lock);
...
sock_orphan(sk);
/*
* proceed with releasing
* the socket
*/
The proposal it to make sock_orphan before detaching the callback
in netlink_release() and to check for the sock to be SOCK_DEAD in
netlink_dump_start() before setting a new callback.
Signed-off-by: Denis Lunev <[EMAIL PROTECTED]>
Signed-off-by: Kirill Korotaev <[EMAIL PROTECTED]>
Signed-off-by: Pavel Emelianov <[EMAIL PROTECTED]>
Acked-by: Patrick McHardy <[EMAIL PROTECTED]>
Signed-off-by: David S. Miller <[EMAIL PROTECTED]>
---
net/netlink/af_netlink.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index e73d8f5..c48b0f4 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -443,6 +443,7 @@ static int netlink_release(struct socket *sock)
return 0;
netlink_remove(sk);
+ sock_orphan(sk);
nlk = nlk_sk(sk);
spin_lock(&nlk->cb_lock);
@@ -457,7 +458,6 @@ static int netlink_release(struct socket *sock)
/* OK. Socket is unlinked, and, therefore,
no new packets will arrive */
- sock_orphan(sk);
sock->sk = NULL;
wake_up_interruptible_all(&nlk->wait);
@@ -1412,9 +1412,9 @@ int netlink_dump_start(struct sock *ssk, struct sk_buff
*skb,
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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