AF_UNIX: Fix deadlock on connecting to shutdown socket (CVE-2009-3621)

[pandora-kernel.git] / net / unix / af_unix.c

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 783317d..facdaa9 100644 (file)
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -8,8 +8,6 @@
  *             as published by the Free Software Foundation; either version
  *             2 of the License, or (at your option) any later version.
  *
- * Version:    $Id: af_unix.c,v 1.133 2002/02/08 03:57:19 davem Exp $
- *
  * Fixes:
  *             Linus Torvalds  :       Assorted bug cures.
  *             Niibe Yutaka    :       async I/O support.
@@ -229,7 +227,7 @@ static void __unix_remove_socket(struct sock *sk)
 
 static void __unix_insert_socket(struct hlist_head *list, struct sock *sk)
 {
-       BUG_TRAP(sk_unhashed(sk));
+       WARN_ON(!sk_unhashed(sk));
        sk_add_node(sk, list);
 }
 
@@ -352,9 +350,9 @@ static void unix_sock_destructor(struct sock *sk)
 
        skb_queue_purge(&sk->sk_receive_queue);
 
-       BUG_TRAP(!atomic_read(&sk->sk_wmem_alloc));
-       BUG_TRAP(sk_unhashed(sk));
-       BUG_TRAP(!sk->sk_socket);
+       WARN_ON(atomic_read(&sk->sk_wmem_alloc));
+       WARN_ON(!sk_unhashed(sk));
+       WARN_ON(sk->sk_socket);
        if (!sock_flag(sk, SOCK_DEAD)) {
                printk("Attempt to release alive unix socket: %p\n", sk);
                return;
@@ -605,7 +603,7 @@ static struct sock * unix_create1(struct net *net, struct socket *sock)
        u->dentry = NULL;
        u->mnt    = NULL;
        spin_lock_init(&u->lock);
-       atomic_set(&u->inflight, 0);
+       atomic_long_set(&u->inflight, 0);
        INIT_LIST_HEAD(&u->link);
        mutex_init(&u->readlock); /* single task reading lock */
        init_waitqueue_head(&u->peer_wait);
@@ -1063,6 +1061,8 @@ restart:
        err = -ECONNREFUSED;
        if (other->sk_state != TCP_LISTEN)
                goto out_unlock;
+       if (other->sk_shutdown & RCV_SHUTDOWN)
+               goto out_unlock;
 
        if (unix_recvq_full(other)) {
                err = -EAGAIN;
@@ -1302,14 +1302,23 @@ static void unix_destruct_fds(struct sk_buff *skb)
        sock_wfree(skb);
 }
 
-static void unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
+static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 {
        int i;
+
+       /*
+        * Need to duplicate file references for the sake of garbage
+        * collection.  Otherwise a socket in the fps might become a
+        * candidate for GC while the skb is not yet queued.
+        */
+       UNIXCB(skb).fp = scm_fp_dup(scm->fp);
+       if (!UNIXCB(skb).fp)
+               return -ENOMEM;
+
        for (i=scm->fp->count-1; i>=0; i--)
                unix_inflight(scm->fp->fp[i]);
-       UNIXCB(skb).fp = scm->fp;
        skb->destructor = unix_destruct_fds;
-       scm->fp = NULL;
+       return 0;
 }
 
 /*
@@ -1334,6 +1343,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
 
        if (NULL == siocb->scm)
                siocb->scm = &tmp_scm;
+       wait_for_unix_gc();
        err = scm_send(sock, msg, siocb->scm);
        if (err < 0)
                return err;
@@ -1368,8 +1378,11 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
                goto out;
 
        memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
-       if (siocb->scm->fp)
-               unix_attach_fds(siocb->scm, skb);
+       if (siocb->scm->fp) {
+               err = unix_attach_fds(siocb->scm, skb);
+               if (err)
+                       goto out_free;
+       }
        unix_get_secdata(siocb->scm, skb);
 
        skb_reset_transport_header(skb);
@@ -1481,6 +1494,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
 
        if (NULL == siocb->scm)
                siocb->scm = &tmp_scm;
+       wait_for_unix_gc();
        err = scm_send(sock, msg, siocb->scm);
        if (err < 0)
                return err;
@@ -1538,8 +1552,13 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                size = min_t(int, size, skb_tailroom(skb));
 
                memcpy(UNIXCREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
-               if (siocb->scm->fp)
-                       unix_attach_fds(siocb->scm, skb);
+               if (siocb->scm->fp) {
+                       err = unix_attach_fds(siocb->scm, skb);
+                       if (err) {
+                               kfree_skb(skb);
+                               goto out_err;
+                       }
+               }
 
                if ((err = memcpy_fromiovec(skb_put(skb,size), msg->msg_iov, size)) != 0) {
                        kfree_skb(skb);
@@ -2213,7 +2232,7 @@ static int unix_net_init(struct net *net)
 #endif
        error = 0;
 out:
-       return 0;
+       return error;
 }
 
 static void unix_net_exit(struct net *net)