diff options
| author | Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> | 2012-07-19 10:13:36 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2012-07-20 22:21:06 +0400 |
| commit | b09e786bd1dd66418b69348cb110f3a64764626a (patch) | |
| tree | e4f12db01edc11d669f32a2d3d6832b22f57f656 | |
| parent | 521f549097a79dc55e18c3bc752ef2127ad70ac5 (diff) | |
| download | linux-b09e786bd1dd66418b69348cb110f3a64764626a.tar.xz | |
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>
| -rw-r--r-- | drivers/net/tun.c | 3 | ||||
| -rw-r--r-- | include/linux/net.h | 1 | ||||
| -rw-r--r-- | net/socket.c | 3 |
3 files changed, 7 insertions, 0 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 961fad1f7053..f3a454c3295a 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); diff --git a/include/linux/net.h b/include/linux/net.h index e9ac2df079ba..dc95700de5df 100644 --- 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 /** 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)); |