From: Cong Wang Date: Fri, 22 Mar 2013 19:14:07 +0000 (+0000) Subject: 8021q: fix a potential use-after-free X-Git-Tag: v3.4.39~21 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a83417946df6c57fbb4d4383c992c5ffd59b56c2;p=karo-tx-linux.git 8021q: fix a potential use-after-free [ Upstream commit 4a7df340ed1bac190c124c1601bfc10cde9fb4fb ] vlan_vid_del() could possibly free ->vlan_info after a RCU grace period, however, we may still refer to the freed memory area by 'grp' pointer. Found by code inspection. This patch moves vlan_vid_del() as behind as possible. Signed-off-by: Cong Wang Cc: Patrick McHardy Cc: "David S. Miller" Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c index cf4a49c5623c..e22b8ada799c 100644 --- a/net/8021q/vlan.c +++ b/net/8021q/vlan.c @@ -86,13 +86,6 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head) grp = &vlan_info->grp; - /* Take it out of our own structures, but be sure to interlock with - * HW accelerating devices or SW vlan input packet processing if - * VLAN is not 0 (leave it there for 802.1p). - */ - if (vlan_id) - vlan_vid_del(real_dev, vlan_id); - grp->nr_vlan_devs--; if (vlan->flags & VLAN_FLAG_GVRP) @@ -108,6 +101,13 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head) if (grp->nr_vlan_devs == 0) vlan_gvrp_uninit_applicant(real_dev); + /* Take it out of our own structures, but be sure to interlock with + * HW accelerating devices or SW vlan input packet processing if + * VLAN is not 0 (leave it there for 802.1p). + */ + if (vlan_id) + vlan_vid_del(real_dev, vlan_id); + /* Get rid of the vlan's reference to real_dev */ dev_put(real_dev); }