[CVE-2013-4343][Raring] tuntap: correctly handle error in tun_set_iff()

[Luis Henriques]

From: Jason Wang <jasowang at redhat.com>

BugLink: http://bugs.launchpad.net/bugs/1229975

CVE-2013-4343

Commit c8d68e6be1c3b242f1c598595830890b65cea64a
(tuntap: multiqueue support) only call free_netdev() on error in
tun_set_iff(). This causes several issues:

- memory of tun security were leaked
- use after free since the flow gc timer was not deleted and the tfile
  were not detached

This patch solves the above issues.

Reported-by: Wannes Rombouts <wannes.rombouts at epitech.eu>
Cc: Michael S. Tsirkin <mst at redhat.com>
Signed-off-by: Jason Wang <jasowang at redhat.com>
Acked-by: Michael S. Tsirkin <mst at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit 662ca437e714caaab855b12415d6ffd815985bc0)
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/tun.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 340cee2..59b46a1 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1684,11 +1684,11 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 		INIT_LIST_HEAD(&tun->disabled);
 		err = tun_attach(tun, file);
 		if (err < 0)
-			goto err_free_dev;
+			goto err_free_flow;
 
 		err = register_netdevice(tun->dev);
 		if (err < 0)
-			goto err_free_dev;
+			goto err_detach;
 
 		if (device_create_file(&tun->dev->dev, &dev_attr_tun_flags) ||
 		    device_create_file(&tun->dev->dev, &dev_attr_owner) ||
@@ -1732,7 +1732,12 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 	strcpy(ifr->ifr_name, tun->dev->name);
 	return 0;
 
- err_free_dev:
+err_detach:
+	tun_detach_all(dev);
+err_free_flow:
+	tun_flow_uninit(tun);
+	security_tun_dev_free_security(tun->security);
+err_free_dev:
 	free_netdev(dev);
 	return err;
 }
-- 
1.8.3.2