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8021q: fix a potential use-after-free

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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.

Cc: Patrick McHardy <kaber@trash.net>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Cong Wang 2013-03-22 19:14:07 +00:00 • committed by David S. Miller
commit 4a7df340ed
1 changed files with 7 additions and 7 deletions
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14
net/8021q/vlan.c
View file

@ -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_MVRP)
@ -114,6 +107,13 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
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);
}