From: Pavel Emelyanov Date: Sun, 11 Nov 2007 06:08:30 +0000 (-0800) Subject: [UNIX]: The unix_nr_socks limit can be exceeded X-Git-Tag: v2.6.24-rc3~155^2~2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=284b327be2f86cf751316ff344b6945e580e654f;p=linux-2.6 [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 Signed-off-by: David S. Miller --- diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index ab9048ac19..e835da8fc0 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -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; }