[PATCH net V2] tuntap: correctly handle error in tun_set_iff()

From: Jason Wang
Date: Wed Sep 11 2013 - 06:21:41 EST


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@xxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
- Changes from V1: shift 1 space for label err_free_netdev and keep
commit log under 70 chars per line.
- The patch were needed for stable kernel 3.8+.
---
drivers/net/tun.c | 11 ++++++++---
1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a639de8..807815f 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1641,11 +1641,11 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
INIT_LIST_HEAD(&tun->disabled);
err = tun_attach(tun, file, false);
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) ||
@@ -1689,7 +1689,12 @@ 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;
}
--
1.7.1

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