netdev - [PATCH net 2/2] net: bridge: mst: fix suspicious rcu usage in br_mst_set

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Date: Sun,  9 Jun 2024 13:36:54 +0300
From: Nikolay Aleksandrov <razor@...ckwall.org>
To: netdev@...r.kernel.org
Cc: tobias@...dekranz.com,
	kuba@...nel.org,
	roopa@...dia.com,
	bridge@...ts.linux.dev,
	edumazet@...gle.com,
	pabeni@...hat.com,
	horms@...nel.org,
	Nikolay Aleksandrov <razor@...ckwall.org>,
	syzbot+9bbe2de1bc9d470eb5fe@...kaller.appspotmail.com
Subject: [PATCH net 2/2] net: bridge: mst: fix suspicious rcu usage in br_mst_set_state

I converted br_mst_set_state to RCU to avoid a vlan use-after-free
but forgot to change the vlan group dereference helper. Switch to vlan
group RCU deref helper to fix the suspicious rcu usage warning.

Fixes: 3a7c1661ae13 ("net: bridge: mst: fix vlan use-after-free")
Reported-by: syzbot+9bbe2de1bc9d470eb5fe@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9bbe2de1bc9d470eb5fe
Signed-off-by: Nikolay Aleksandrov <razor@...ckwall.org>
---
 net/bridge/br_mst.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_mst.c b/net/bridge/br_mst.c
index 1de72816b0fb..1820f09ff59c 100644
--- a/net/bridge/br_mst.c
+++ b/net/bridge/br_mst.c
@@ -102,7 +102,7 @@ int br_mst_set_state(struct net_bridge_port *p, u16 msti, u8 state,
 	int err = 0;
 
 	rcu_read_lock();
-	vg = nbp_vlan_group(p);
+	vg = nbp_vlan_group_rcu(p);
 	if (!vg)
 		goto out;
 
-- 
2.45.1