From 468e7944589c7f096bb4ea14db17980aa6c2766c Mon Sep 17 00:00:00 2001 From: Nikolay Aleksandrov Date: Wed, 30 Sep 2015 20:16:52 +0200 Subject: [PATCH] bridge: vlan: fix possible null vlgrp deref while registering new port While a new port is being initialized the rx_handler gets set, but the vlans get initialized later in br_add_if() and in that window if we receive a frame with a link-local address we can try to dereference p->vlgrp in: br_handle_frame() -> br_handle_local_finish() -> br_should_learn() Fix this by checking vlgrp before using it. Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller --- net/bridge/br_vlan.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c index 283d012c3d89..678d5c41b551 100644 --- a/net/bridge/br_vlan.c +++ b/net/bridge/br_vlan.c @@ -476,13 +476,15 @@ bool br_allowed_egress(struct net_bridge_vlan_group *vg, /* Called under RCU */ bool br_should_learn(struct net_bridge_port *p, struct sk_buff *skb, u16 *vid) { + struct net_bridge_vlan_group *vg; struct net_bridge *br = p->br; /* If filtering was disabled at input, let it pass. */ if (!br->vlan_enabled) return true; - if (!p->vlgrp->num_vlans) + vg = p->vlgrp; + if (!vg || !vg->num_vlans) return false; if (!br_vlan_get_tag(skb, vid) && skb->vlan_proto != br->vlan_proto) -- 2.20.1