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authorMikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>2012-07-19 06:13:36 +0000
committerDavid S. Miller <davem@davemloft.net>2012-07-20 11:21:06 -0700
commitb09e786bd1dd66418b69348cb110f3a64764626a (patch)
treee4f12db01edc11d669f32a2d3d6832b22f57f656 /drivers/net
parent521f549097a79dc55e18c3bc752ef2127ad70ac5 (diff)
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 <mikulas@artax.karlin.mff.cuni.cz> Cc: stable@kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/tun.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 961fad1f705..f3a454c3295 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -358,6 +358,8 @@ static void tun_free_netdev(struct net_device *dev)
{
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, struct file *file, struct ifreq *ifr)
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);