vlan: Fix VLAN 0 memory leak

The referenced commit intended to fix memleak of VLAN 0 that is implicitly
created on devices with NETIF_F_HW_VLAN_CTAG_FILTER feature. However, it
doesn't take into account that the feature can be re-set during the
netdevice lifetime which will cause memory leak if feature is disabled
during the device deletion as illustrated by [0]. Fix the leak by
unconditionally deleting VLAN 0 on NETDEV_DOWN event.

[0]:
> modprobe 8021q
> ip l set dev eth2 up
> ethtool -K eth2 rx-vlan-filter off
> modprobe -r mlx5_ib
> modprobe -r mlx5_core
> cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff888103dcd900 (size 256):
  comm "ip", pid 1490, jiffies 4294907305 (age 325.364s)
  hex dump (first 32 bytes):
    00 80 5d 03 81 88 ff ff 00 00 00 00 00 00 00 00  ..].............
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000899f3bb9>] kmalloc_trace+0x25/0x80
    [<000000002889a7a2>] vlan_vid_add+0xa0/0x210
    [<000000007177800e>] vlan_device_event+0x374/0x760 [8021q]
    [<000000009a0716b1>] notifier_call_chain+0x35/0xb0
    [<00000000bbf3d162>] __dev_notify_flags+0x58/0xf0
    [<0000000053d2b05d>] dev_change_flags+0x4d/0x60
    [<00000000982807e9>] do_setlink+0x28d/0x10a0
    [<0000000058c1be00>] __rtnl_newlink+0x545/0x980
    [<00000000e66c3bd9>] rtnl_newlink+0x44/0x70
    [<00000000a2cc5970>] rtnetlink_rcv_msg+0x29c/0x390
    [<00000000d307d1e4>] netlink_rcv_skb+0x54/0x100
    [<00000000259d16f9>] netlink_unicast+0x1f6/0x2c0
    [<000000007ce2afa1>] netlink_sendmsg+0x232/0x4a0
    [<00000000f3f4bb39>] sock_sendmsg+0x38/0x60
    [<000000002f9c0624>] ____sys_sendmsg+0x1e3/0x200
    [<00000000d6ff5520>] ___sys_sendmsg+0x80/0xc0
unreferenced object 0xffff88813354fde0 (size 32):
  comm "ip", pid 1490, jiffies 4294907305 (age 325.364s)
  hex dump (first 32 bytes):
    a0 d9 dc 03 81 88 ff ff a0 d9 dc 03 81 88 ff ff  ................
    81 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000899f3bb9>] kmalloc_trace+0x25/0x80
    [<000000002da64724>] vlan_vid_add+0xdf/0x210
    [<000000007177800e>] vlan_device_event+0x374/0x760 [8021q]
    [<000000009a0716b1>] notifier_call_chain+0x35/0xb0
    [<00000000bbf3d162>] __dev_notify_flags+0x58/0xf0
    [<0000000053d2b05d>] dev_change_flags+0x4d/0x60
    [<00000000982807e9>] do_setlink+0x28d/0x10a0
    [<0000000058c1be00>] __rtnl_newlink+0x545/0x980
    [<00000000e66c3bd9>] rtnl_newlink+0x44/0x70
    [<00000000a2cc5970>] rtnetlink_rcv_msg+0x29c/0x390
    [<00000000d307d1e4>] netlink_rcv_skb+0x54/0x100
    [<00000000259d16f9>] netlink_unicast+0x1f6/0x2c0
    [<000000007ce2afa1>] netlink_sendmsg+0x232/0x4a0
    [<00000000f3f4bb39>] sock_sendmsg+0x38/0x60
    [<000000002f9c0624>] ____sys_sendmsg+0x1e3/0x200
    [<00000000d6ff5520>] ___sys_sendmsg+0x80/0xc0

Fixes: efc73f4b ("net: Fix memory leak - vlan_info struct")
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Vlad Buslov <vladbu@nvidia.com>
Link: https://lore.kernel.org/r/20230808093521.1468929-1-vladbu@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/8021q/vlan.c

@@ -384,8 +384,7 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
 			dev->name);
 		vlan_vid_add(dev, htons(ETH_P_8021Q), 0);
 	}
-	if (event == NETDEV_DOWN &&
-	    (dev->features & NETIF_F_HW_VLAN_CTAG_FILTER))
+	if (event == NETDEV_DOWN)
 		vlan_vid_del(dev, htons(ETH_P_8021Q), 0);
 
 	vlan_info = rtnl_dereference(dev->vlan_info);