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[UNIX]: The unix_nr_socks limit can be exceeded 

The unix_nr_socks value is limited with the 2 * get_max_files() value,
as seen from the unix_create1(). However, the check and the actual
increment are separated with the GFP_KERNEL allocation, so this limit
can be exceeded under a memory pressure - task may go to sleep freeing
the pages and some other task will be allowed to allocate a new sock
and so on and so forth.

So make the increment before the check (similar thing is done in the
sock_kmalloc) and go to kmalloc after this.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pavel Emelyanov 2007-11-10 22:08:30 -08:00 committed by David S. Miller
parent 5c80f1ae98
commit 284b327be2
1 changed files with 4 additions and 3 deletions
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7
net/unix/af_unix.c
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@ -599,15 +599,14 @@ static struct sock * unix_create1(struct net *net, struct socket *sock)
struct sock *sk = NULL;
struct unix_sock *u;
if (atomic_read(&unix_nr_socks) >= 2*get_max_files())
atomic_inc(&unix_nr_socks);
if (atomic_read(&unix_nr_socks) > 2 * get_max_files())
goto out;
sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_proto);
if (!sk)
goto out;
atomic_inc(&unix_nr_socks);
sock_init_data(sock,sk);
lockdep_set_class(&sk->sk_receive_queue.lock,
&af_unix_sk_receive_queue_lock_key);
@ -625,6 +624,8 @@ static struct sock * unix_create1(struct net *net, struct socket *sock)
init_waitqueue_head(&u->peer_wait);
unix_insert_socket(unix_sockets_unbound, sk);
out:
if (sk == NULL)
atomic_dec(&unix_nr_socks);
return sk;
}