On initialization failure we have to delete the local fdb which was
inserted due to the default pvid creation. This problem has been present
since the inception of default_pvid. Note that currently there are 2 cases:
1) in br_dev_init() when br_multicast_init() fails
2) if register_netdevice() fails after calling ndo_init()
This patch takes care of both since br_vlan_flush() is called on both
occasions. Also the new fdb delete would be a no-op on normal bridge
device destruction since the local fdb would've been already flushed by
br_dev_delete(). This is not an issue for ports since nbp_vlan_init() is
called last when adding a port thus nothing can fail after it.
Reported-by: syzbot+88533dc8b582309bf3ee@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 5be5a2df40f0 ("bridge: Add filtering support for default_pvid")
Signed-off-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx>
---
v2: reworded the commit message and comment so they're not plural, we're
talking about a single bridge local fdb added on the init vlan creation
of the default pvid
Tested with the provided reproducer and can no longer trigger the leak.
Also tested the br_multicast_init() failure manually by making it always
return an error.
net/bridge/br_vlan.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index 021cc9f66804..3e6a702e4c21 100644
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -715,6 +715,11 @@ void br_vlan_flush(struct net_bridge *br)
ASSERT_RTNL();
+ /* delete auto-added default pvid local fdb before flushing vlans
+ * otherwise it will be leaked on bridge device init failure
+ */
+ br_fdb_delete_by_port(br, NULL, 0, 1);
+
vg = br_vlan_group(br);
__vlan_flush(vg);
RCU_INIT_POINTER(br->vlgrp, NULL);
--
2.21.0
