From f0a4d0e5b5bfd271e6737f7c095994835b70d450 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 8 Jun 2009 00:44:31 -0700 Subject: [PATCH] tun: Fix unregister race It is possible for tun_chr_close to race with dellink on the a tun device. In which case if __tun_get runs before dellink but dellink runs before tun_chr_close calls unregister_netdevice we will attempt to unregister the netdevice after it is already gone. The two cases are already serialized on the rtnl_lock, so I have gone for the cheap simple fix of moving rtnl_lock to cover __tun_get in tun_chr_close. Eliminating the possibility of the tun device being unregistered between __tun_get and unregister_netdevice in tun_chr_close. Signed-off-by: Eric W. Biederman Tested-by: David Woodhouse Signed-off-by: David S. Miller --- drivers/net/tun.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index d83ccb8c982b..811d3517fce0 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1322,21 +1322,22 @@ static int tun_chr_open(struct inode *inode, struct file * file) static int tun_chr_close(struct inode *inode, struct file *file) { struct tun_file *tfile = file->private_data; - struct tun_struct *tun = __tun_get(tfile); + struct tun_struct *tun; + rtnl_lock(); + tun = __tun_get(tfile); if (tun) { DBG(KERN_INFO "%s: tun_chr_close\n", tun->dev->name); - rtnl_lock(); __tun_detach(tun); /* If desireable, unregister the netdevice. */ if (!(tun->flags & TUN_PERSIST)) unregister_netdevice(tun->dev); - rtnl_unlock(); } + rtnl_unlock(); tun = tfile->tun; if (tun)