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| 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 /drivers/net/tun.c | |
| 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>
Diffstat (limited to 'drivers/net/tun.c')
| -rw-r--r-- | drivers/net/tun.c | 3 |
1 files changed, 3 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); |