From 36c92936e868601fa1f43da6758cf55805043509 Mon Sep 17 00:00:00 2001 From: Nikolay Aleksandrov Date: Sun, 9 Jun 2024 13:36:53 +0300 Subject: [PATCH 1/2] net: bridge: mst: pass vlan group directly to br_mst_vlan_set_state Pass the already obtained vlan group pointer to br_mst_vlan_set_state() instead of dereferencing it again. Each caller has already correctly dereferenced it for their context. This change is required for the following suspicious RCU dereference fix. No functional changes intended. Fixes: 3a7c1661ae13 ("net: bridge: mst: fix vlan use-after-free") Reported-by: syzbot+9bbe2de1bc9d470eb5fe@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9bbe2de1bc9d470eb5fe Signed-off-by: Nikolay Aleksandrov Link: https://lore.kernel.org/r/20240609103654.914987-2-razor@blackwall.org Signed-off-by: Jakub Kicinski --- net/bridge/br_mst.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/net/bridge/br_mst.c b/net/bridge/br_mst.c index 3c66141d34d62f..1de72816b0fb25 100644 --- a/net/bridge/br_mst.c +++ b/net/bridge/br_mst.c @@ -73,11 +73,10 @@ int br_mst_get_state(const struct net_device *dev, u16 msti, u8 *state) } EXPORT_SYMBOL_GPL(br_mst_get_state); -static void br_mst_vlan_set_state(struct net_bridge_port *p, struct net_bridge_vlan *v, +static void br_mst_vlan_set_state(struct net_bridge_vlan_group *vg, + struct net_bridge_vlan *v, u8 state) { - struct net_bridge_vlan_group *vg = nbp_vlan_group(p); - if (br_vlan_get_state(v) == state) return; @@ -121,7 +120,7 @@ int br_mst_set_state(struct net_bridge_port *p, u16 msti, u8 state, if (v->brvlan->msti != msti) continue; - br_mst_vlan_set_state(p, v, state); + br_mst_vlan_set_state(vg, v, state); } out: @@ -140,13 +139,13 @@ static void br_mst_vlan_sync_state(struct net_bridge_vlan *pv, u16 msti) * it. */ if (v != pv && v->brvlan->msti == msti) { - br_mst_vlan_set_state(pv->port, pv, v->state); + br_mst_vlan_set_state(vg, pv, v->state); return; } } /* Otherwise, start out in a new MSTI with all ports disabled. */ - return br_mst_vlan_set_state(pv->port, pv, BR_STATE_DISABLED); + return br_mst_vlan_set_state(vg, pv, BR_STATE_DISABLED); } int br_mst_vlan_set_msti(struct net_bridge_vlan *mv, u16 msti) From 546ceb1dfdac866648ec959cbc71d9525bd73462 Mon Sep 17 00:00:00 2001 From: Nikolay Aleksandrov Date: Sun, 9 Jun 2024 13:36:54 +0300 Subject: [PATCH 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@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9bbe2de1bc9d470eb5fe Signed-off-by: Nikolay Aleksandrov Link: https://lore.kernel.org/r/20240609103654.914987-3-razor@blackwall.org Signed-off-by: Jakub Kicinski --- 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 1de72816b0fb25..1820f09ff59ceb 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;