From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933098Ab2HGXNu (ORCPT ); Tue, 7 Aug 2012 19:13:50 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:42716 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932960Ab2HGWhz (ORCPT ); Tue, 7 Aug 2012 18:37:55 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg KH , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Mikulas Patocka , "David S. Miller" Subject: [ 033/109] tun: fix a crash bug and a memory leak Date: Tue, 7 Aug 2012 15:34:52 -0700 Message-Id: <20120807222046.007998429@linuxfoundation.org> X-Mailer: git-send-email 1.7.10.1.362.g242cab3 In-Reply-To: <20120807222043.089735600@linuxfoundation.org> References: <20120807222043.089735600@linuxfoundation.org> User-Agent: quilt/0.60-20.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg KH 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit b09e786bd1dd66418b69348cb110f3a64764626a upstream. This patch fixes a crash tun_chr_close -> netdev_run_todo -> tun_free_netdev -> sk_release_kernel -> sock_release -> iput(SOCK_INODE(sock)) introduced by commit 1ab5ecb90cb6a3df1476e052f76a6e8f6511cb3d The problem is that this socket is embedded in struct tun_struct, it has no inode, iput is called on invalid inode, which modifies invalid memory and optionally causes a crash. sock_release also decrements sockets_in_use, this causes a bug that "sockets: used" field in /proc/*/net/sockstat keeps on decreasing when creating and closing tun devices. This patch introduces a flag SOCK_EXTERNALLY_ALLOCATED that instructs sock_release to not free the inode and not decrement sockets_in_use, fixing both memory corruption and sockets_in_use underflow. It should be backported to 3.3 an 3.4 stabke. Signed-off-by: Mikulas Patocka Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/tun.c | 3 +++ include/linux/net.h | 1 + net/socket.c | 3 +++ 3 files changed, 7 insertions(+) --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -358,6 +358,8 @@ static void tun_free_netdev(struct net_d { struct tun_struct *tun = netdev_priv(dev); + BUG_ON(!test_bit(SOCK_EXTERNALLY_ALLOCATED, &tun->socket.flags)); + sk_release_kernel(tun->socket.sk); } @@ -1115,6 +1117,7 @@ static int tun_set_iff(struct net *net, tun->flags = flags; tun->txflt.count = 0; tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr); + set_bit(SOCK_EXTERNALLY_ALLOCATED, &tun->socket.flags); err = -ENOMEM; sk = sk_alloc(&init_net, AF_UNSPEC, GFP_KERNEL, &tun_proto); --- a/include/linux/net.h +++ b/include/linux/net.h @@ -72,6 +72,7 @@ struct net; #define SOCK_NOSPACE 2 #define SOCK_PASSCRED 3 #define SOCK_PASSSEC 4 +#define SOCK_EXTERNALLY_ALLOCATED 5 #ifndef ARCH_HAS_SOCKET_TYPES /** --- a/net/socket.c +++ b/net/socket.c @@ -522,6 +522,9 @@ void sock_release(struct socket *sock) if (rcu_dereference_protected(sock->wq, 1)->fasync_list) printk(KERN_ERR "sock_release: fasync list not empty!\n"); + if (test_bit(SOCK_EXTERNALLY_ALLOCATED, &sock->flags)) + return; + percpu_sub(sockets_in_use, 1); if (!sock->file) { iput(SOCK_INODE(sock));