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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 /net/socket.c
parent521f549097a79dc55e18c3bc752ef2127ad70ac5 (diff)
downloadlinux-b09e786bd1dd66418b69348cb110f3a64764626a.tar.gz
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 'net/socket.c')
-rw-r--r--net/socket.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/net/socket.c b/net/socket.c
index 6e0ccc09b31..0452dca4cd2 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));