From b09e786bd1dd66418b69348cb110f3a64764626a Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Thu, 19 Jul 2012 06:13:36 +0000 Subject: tun: fix a crash bug and a memory leak 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 Cc: stable@kernel.org Signed-off-by: David S. Miller --- net/socket.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/socket.c') diff --git a/net/socket.c b/net/socket.c index 6e0ccc09b313..0452dca4cd24 100644 --- 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; + this_cpu_sub(sockets_in_use, 1); if (!sock->file) { iput(SOCK_INODE(sock)); -- cgit v1.2.3-59-g8ed1b