[PATCH net] bonding: Fix memory leak when changing bond type to Ethernet

[Ido Schimmel <idosch@nvidia.com>]

When a net device is put administratively up, its 'IFF_UP' flag is set
(if not set already) and a 'NETDEV_UP' notification is emitted, which
causes the 8021q driver to add VLAN ID 0 on the device. The reverse
happens when a net device is put administratively down.

When changing the type of a bond to Ethernet, its 'IFF_UP' flag is
incorrectly cleared, resulting in the kernel skipping the above process
and VLAN ID 0 being leaked [1].

Fix by restoring the flag when changing the type to Ethernet, in a
similar fashion to the restoration of the 'IFF_SLAVE' flag.

The issue can be reproduced using the script in [2], with example out
before and after the fix in [3].

[1]
unreferenced object 0xffff888103479900 (size 256):
  comm "ip", pid 329, jiffies 4294775225 (age 28.561s)
  hex dump (first 32 bytes):
    00 a0 0c 15 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:
    [<ffffffff81a6051a>] kmalloc_trace+0x2a/0xe0
    [<ffffffff8406426c>] vlan_vid_add+0x30c/0x790
    [<ffffffff84068e21>] vlan_device_event+0x1491/0x21a0
    [<ffffffff81440c8e>] notifier_call_chain+0xbe/0x1f0
    [<ffffffff8372383a>] call_netdevice_notifiers_info+0xba/0x150
    [<ffffffff837590f2>] __dev_notify_flags+0x132/0x2e0
    [<ffffffff8375ad9f>] dev_change_flags+0x11f/0x180
    [<ffffffff8379af36>] do_setlink+0xb96/0x4060
    [<ffffffff837adf6a>] __rtnl_newlink+0xc0a/0x18a0
    [<ffffffff837aec6c>] rtnl_newlink+0x6c/0xa0
    [<ffffffff837ac64e>] rtnetlink_rcv_msg+0x43e/0xe00
    [<ffffffff839a99e0>] netlink_rcv_skb+0x170/0x440
    [<ffffffff839a738f>] netlink_unicast+0x53f/0x810
    [<ffffffff839a7fcb>] netlink_sendmsg+0x96b/0xe90
    [<ffffffff8369d12f>] ____sys_sendmsg+0x30f/0xa70
    [<ffffffff836a6d7a>] ___sys_sendmsg+0x13a/0x1e0
unreferenced object 0xffff88810f6a83e0 (size 32):
  comm "ip", pid 329, jiffies 4294775225 (age 28.561s)
  hex dump (first 32 bytes):
    a0 99 47 03 81 88 ff ff a0 99 47 03 81 88 ff ff  ..G.......G.....
    81 00 00 00 01 00 00 00 cc cc cc cc cc cc cc cc  ................
  backtrace:
    [<ffffffff81a6051a>] kmalloc_trace+0x2a/0xe0
    [<ffffffff84064369>] vlan_vid_add+0x409/0x790
    [<ffffffff84068e21>] vlan_device_event+0x1491/0x21a0
    [<ffffffff81440c8e>] notifier_call_chain+0xbe/0x1f0
    [<ffffffff8372383a>] call_netdevice_notifiers_info+0xba/0x150
    [<ffffffff837590f2>] __dev_notify_flags+0x132/0x2e0
    [<ffffffff8375ad9f>] dev_change_flags+0x11f/0x180
    [<ffffffff8379af36>] do_setlink+0xb96/0x4060
    [<ffffffff837adf6a>] __rtnl_newlink+0xc0a/0x18a0
    [<ffffffff837aec6c>] rtnl_newlink+0x6c/0xa0
    [<ffffffff837ac64e>] rtnetlink_rcv_msg+0x43e/0xe00
    [<ffffffff839a99e0>] netlink_rcv_skb+0x170/0x440
    [<ffffffff839a738f>] netlink_unicast+0x53f/0x810
    [<ffffffff839a7fcb>] netlink_sendmsg+0x96b/0xe90
    [<ffffffff8369d12f>] ____sys_sendmsg+0x30f/0xa70
    [<ffffffff836a6d7a>] ___sys_sendmsg+0x13a/0x1e0

[2]
ip link add name t-nlmon type nlmon
ip link add name t-dummy type dummy
ip link add name t-bond type bond mode active-backup

ip link set dev t-bond up
ip link set dev t-nlmon master t-bond
ip link set dev t-nlmon nomaster
ip link show dev t-bond
ip link set dev t-dummy master t-bond
ip link show dev t-bond

ip link del dev t-bond
ip link del dev t-dummy
ip link del dev t-nlmon

[3]
Before:

12: t-bond: <NO-CARRIER,BROADCAST,MULTICAST,MASTER,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default qlen 1000
    link/netlink
12: t-bond: <BROADCAST,MULTICAST,MASTER,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 46:57:39:a4:46:a2 brd ff:ff:ff:ff:ff:ff

After:

12: t-bond: <NO-CARRIER,BROADCAST,MULTICAST,MASTER,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default qlen 1000
    link/netlink
12: t-bond: <BROADCAST,MULTICAST,MASTER,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
    link/ether 66:48:7b:74:b6:8a brd ff:ff:ff:ff:ff:ff

Fixes: e36b9d16c6a6 ("bonding: clean muticast addresses when device changes type")
Fixes: 75c78500ddad ("bonding: remap muticast addresses without using dev_close() and dev_open()")
Fixes: 9ec7eb60dcbc ("bonding: restore IFF_MASTER/SLAVE flags on bond enslave ether type change")
Reported-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Link: https://lore.kernel.org/netdev/78a8a03b-6070-3e6b-5042-f848dab16fb8@alu.unizg.hr/
Tested-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 drivers/net/bonding/bond_main.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 8cc9a74789b7..7a7d584f378a 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1777,14 +1777,15 @@ void bond_lower_state_changed(struct slave *slave)
 
 /* The bonding driver uses ether_setup() to convert a master bond device
  * to ARPHRD_ETHER, that resets the target netdevice's flags so we always
- * have to restore the IFF_MASTER flag, and only restore IFF_SLAVE if it was set
+ * have to restore the IFF_MASTER flag, and only restore IFF_SLAVE and IFF_UP
+ * if they were set
  */
 static void bond_ether_setup(struct net_device *bond_dev)
 {
-	unsigned int slave_flag = bond_dev->flags & IFF_SLAVE;
+	unsigned int flags = bond_dev->flags & (IFF_SLAVE | IFF_UP);
 
 	ether_setup(bond_dev);
-	bond_dev->flags |= IFF_MASTER | slave_flag;
+	bond_dev->flags |= IFF_MASTER | flags;
 	bond_dev->priv_flags &= ~IFF_TX_SKB_SHARING;
 }
 
-- 
2.37.3