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tuntap: fix leaking reference count

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Reference count leaking of both module and sock were found:

- When a detached file were closed, its sock refcnt from device were not
  released, solving this by add the sock_put().
- The module were hold or drop unconditionally in TUNSETPERSIST, which means we
  if we set the persist flag for N times, we need unset it for another N
  times. Solving this by only hold or drop an reference when there's a flag
  change and also drop the reference count when the persist device is deleted.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2013-01-11 16:59:34 +00:00 committed by David S. Miller
parent 7c0c3b1a8a
commit dd38bd8530
1 changed files with 9 additions and 3 deletions
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12
drivers/net/tun.c
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@ -428,8 +428,10 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
/* Drop read queue */
skb_queue_purge(&tfile->sk.sk_receive_queue);
tun_set_real_num_queues(tun);
} else if (tfile->detached && clean)
} else if (tfile->detached && clean) {
tun = tun_enable_queue(tfile);
sock_put(&tfile->sk);
}
if (clean) {
if (tun && tun->numqueues == 0 && tun->numdisabled == 0 &&
@ -478,6 +480,9 @@ static void tun_detach_all(struct net_device *dev)
sock_put(&tfile->sk);
}
BUG_ON(tun->numdisabled != 0);
if (tun->flags & TUN_PERSIST)
module_put(THIS_MODULE);
}
static int tun_attach(struct tun_struct *tun, struct file *file)
@ -1874,10 +1879,11 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
/* Disable/Enable persist mode. Keep an extra reference to the
* module to prevent the module being unprobed.
*/
if (arg) {
if (arg && !(tun->flags & TUN_PERSIST)) {
tun->flags |= TUN_PERSIST;
__module_get(THIS_MODULE);
} else {
}
if (!arg && (tun->flags & TUN_PERSIST)) {
tun->flags &= ~TUN_PERSIST;
module_put(THIS_MODULE);
}