From: Nikolay Aleksandrov nikolay@cumulusnetworks.com
[ Upstream commit c4b4c421857dc7b1cf0dccbd738472360ff2cd70 ]
We have an interesting memory leak in the bridge when it is being unregistered and is a slave to a master device which would change the mac of its slaves on unregister (e.g. bond, team). This is a very unusual setup but we do end up leaking 1 fdb entry because dev_set_mac_address() would cause the bridge to insert the new mac address into its table after all fdbs are flushed, i.e. after dellink() on the bridge has finished and we call NETDEV_UNREGISTER the bond/team would release it and will call dev_set_mac_address() to restore its original address and that in turn will add an fdb in the bridge. One fix is to check for the bridge dev's reg_state in its ndo_set_mac_address callback and return an error if the bridge is not in NETREG_REGISTERED.
Easy steps to reproduce: 1. add bond in mode != A/B 2. add any slave to the bond 3. add bridge dev as a slave to the bond 4. destroy the bridge device
Trace: unreferenced object 0xffff888035c4d080 (size 128): comm "ip", pid 4068, jiffies 4296209429 (age 1413.753s) hex dump (first 32 bytes): 41 1d c9 36 80 88 ff ff 00 00 00 00 00 00 00 00 A..6............ d2 19 c9 5e 3f d7 00 00 00 00 00 00 00 00 00 00 ...^?........... backtrace: [<00000000ddb525dc>] kmem_cache_alloc+0x155/0x26f [<00000000633ff1e0>] fdb_create+0x21/0x486 [bridge] [<0000000092b17e9c>] fdb_insert+0x91/0xdc [bridge] [<00000000f2a0f0ff>] br_fdb_change_mac_address+0xb3/0x175 [bridge] [<000000001de02dbd>] br_stp_change_bridge_id+0xf/0xff [bridge] [<00000000ac0e32b1>] br_set_mac_address+0x76/0x99 [bridge] [<000000006846a77f>] dev_set_mac_address+0x63/0x9b [<00000000d30738fc>] __bond_release_one+0x3f6/0x455 [bonding] [<00000000fc7ec01d>] bond_netdev_event+0x2f2/0x400 [bonding] [<00000000305d7795>] notifier_call_chain+0x38/0x56 [<0000000028885d4a>] call_netdevice_notifiers+0x1e/0x23 [<000000008279477b>] rollback_registered_many+0x353/0x6a4 [<0000000018ef753a>] unregister_netdevice_many+0x17/0x6f [<00000000ba854b7a>] rtnl_delete_link+0x3c/0x43 [<00000000adf8618d>] rtnl_dellink+0x1dc/0x20a [<000000009b6395fd>] rtnetlink_rcv_msg+0x23d/0x268
Fixes: 43598813386f ("bridge: add local MAC address to forwarding table (v2)") Reported-by: syzbot+2add91c08eb181fea1bf@syzkaller.appspotmail.com Signed-off-by: Nikolay Aleksandrov nikolay@cumulusnetworks.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/bridge/br_device.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/net/bridge/br_device.c +++ b/net/bridge/br_device.c @@ -246,6 +246,12 @@ static int br_set_mac_address(struct net if (!is_valid_ether_addr(addr->sa_data)) return -EADDRNOTAVAIL;
+ /* dev_set_mac_addr() can be called by a master device on bridge's + * NETDEV_UNREGISTER, but since it's being destroyed do nothing + */ + if (dev->reg_state != NETREG_REGISTERED) + return -EBUSY; + spin_lock_bh(&br->lock); if (!ether_addr_equal(dev->dev_addr, addr->sa_data)) { /* Mac address will be changed in br_stp_change_bridge_id(). */