[PATCH AUTOSEL for 4.9 36/52] macvlan: Fix one possible double free

Sasha Levin
2018-02-03T18:08:17Z

From: Gao Feng <gfree.wind@vip.163.com>

[ Upstream commit d02fd6e7d2933ede6478a15f9e4ce8a93845824e ]

Because the macvlan_uninit would free the macvlan port, so there is one
double free case in macvlan_common_newlink. When the macvlan port is just
created, then register_netdevice or netdev_upper_dev_link failed and they
would invoke macvlan_uninit. Then it would reach the macvlan_port_destroy
which triggers the double free.

Signed-off-by: Gao Feng <gfree.wind@vip.163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/net/macvlan.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 6d55049cd3dc..e8ad4d060da7 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -1377,9 +1377,14 @@ int macvlan_common_newlink(struct net *src_net, struct net_device *dev,
return 0;

unregister_netdev:
+ /* macvlan_uninit would free the macvlan port */
unregister_netdevice(dev);
+ return err;
destroy_macvlan_port:
- if (create)
+ /* the macvlan port may be freed by macvlan_uninit when fail to register.
+ * so we destroy the macvlan port only when it's valid.
+ */
+ if (create && macvlan_port_get_rtnl(dev))
macvlan_port_destroy(port->dev);
return err;
}
--
2.11.0