8021q: fix a potential use-after-free
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>
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@ -86,13 +86,6 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
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grp = &vlan_info->grp;
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/* Take it out of our own structures, but be sure to interlock with
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* HW accelerating devices or SW vlan input packet processing if
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* VLAN is not 0 (leave it there for 802.1p).
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*/
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if (vlan_id)
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vlan_vid_del(real_dev, vlan_id);
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grp->nr_vlan_devs--;
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if (vlan->flags & VLAN_FLAG_MVRP)
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@ -114,6 +107,13 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
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vlan_gvrp_uninit_applicant(real_dev);
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}
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/* Take it out of our own structures, but be sure to interlock with
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* HW accelerating devices or SW vlan input packet processing if
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* VLAN is not 0 (leave it there for 802.1p).
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*/
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if (vlan_id)
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vlan_vid_del(real_dev, vlan_id);
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/* Get rid of the vlan's reference to real_dev */
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dev_put(real_dev);
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}
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