linux-kernel - [PATCH] net-bridge: fix unsafe dereference of potential null ptr in __vlan

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Message-Id: <20230217131657.12649-1-alsp705@gmail.com>
Date:   Fri, 17 Feb 2023 16:16:57 +0300
From:   Alexander Sapozhnikov <alsp705@...il.com>
To:     Roopa Prabhu <roopa@...dia.com>
Cc:     Alexander Sapozhnikov <alsp705@...il.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        bridge@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: [PATCH] net-bridge: fix unsafe dereference of potential null ptr in __vlan_del() 

After having been compared to NULL value at br_vlan.c:399,
pointer 'p' is passed as 1st parameter in call to function
'nbp_vlan_set_vlan_dev_state' at br_vlan.c:420, 
where it is dereferenced at br_vlan.c:1722.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Alexander Sapozhnikov <alsp705@...il.com>
---
 net/bridge/br_vlan.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index bc75fa1e4666..87091e270adf 100644
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -417,7 +417,8 @@ static int __vlan_del(struct net_bridge_vlan *v)
 		rhashtable_remove_fast(&vg->vlan_hash, &v->vnode,
 				       br_vlan_rht_params);
 		__vlan_del_list(v);
-		nbp_vlan_set_vlan_dev_state(p, v->vid);
+		if (p)
+			nbp_vlan_set_vlan_dev_state(p, v->vid);
 		br_multicast_toggle_one_vlan(v, false);
 		br_multicast_port_ctx_deinit(&v->port_mcast_ctx);
 		call_rcu(&v->rcu, nbp_vlan_rcu_free);
-- 
2.34.1