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>
diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index a187144..85addcd 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -86,13 +86,6 @@
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 @@
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);
}