| From foo@baz Wed 18 Dec 2019 01:37:17 PM CET |
| From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> |
| Date: Tue, 3 Dec 2019 16:48:06 +0200 |
| Subject: net: bridge: deny dev_set_mac_address() when unregistering |
| |
| 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 |
| @@ -198,6 +198,12 @@ 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(). */ |