This is a note to let you know that I've just added the patch titled

i40e: don't remove netdev->dev_addr when syncing uc list

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: i40e-don-t-remove-netdev-dev_addr-when-syncing-uc-list.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Wed Feb 28 16:23:28 CET 2018

From: Jacob Keller jacob.e.keller@intel.com Date: Wed, 20 Dec 2017 11:04:36 -0500 Subject: i40e: don't remove netdev->dev_addr when syncing uc list

From: Jacob Keller jacob.e.keller@intel.com

[ Upstream commit 458867b2ca0c987445c5d9adccd1642970e1ba07 ]

In some circumstances, such as with bridging, it is possible that the stack will add a devices own MAC address to its unicast address list.

If, later, the stack deletes this address, then the i40e driver will receive a request to remove this address.

The driver stores its current MAC address as part of the MAC/VLAN hash array, since it is convenient and matches exactly how the hardware expects to be told which traffic to receive.

This causes a problem, since for more devices, the MAC address is stored separately, and requests to delete a unicast address should not have the ability to remove the filter for the MAC address.

Fix this by forcing a check on every address sync to ensure we do not remove the device address.

There is a very narrow possibility of a race between .set_mac and .set_rx_mode, if we don't change netdev->dev_addr before updating our internal MAC list in .set_mac. This might be possible if .set_rx_mode is going to remove MAC "XYZ" from the list, at the same time as .set_mac changes our dev_addr to MAC "XYZ", we might possibly queue a delete, then an add in .set_mac, then queue a delete in .set_rx_mode's dev_uc_sync and then update netdev->dev_addr. We can avoid this by moving the copy into dev_addr prior to the changes to the MAC filter list.

A similar race on the other side does not cause problems, as if we're changing our MAC form A to B, and we race with .set_rx_mode, it could queue a delete from A, we'd update our address, and allow the delete. This seems like a race, but in reality we're about to queue a delete of A anyways, so it would not cause any issues.

A race in the initialization code is unlikely because the netdevice has not yet been fully initialized and the stack should not be adding or removing addresses yet.

Note that we don't (yet) need similar code for the VF driver because it does not make use of __dev_uc_sync and __dev_mc_sync, but instead roles its own method for handling updates to the MAC/VLAN list, which already has code to protect against removal of the hardware address.

Signed-off-by: Jacob Keller jacob.e.keller@intel.com Tested-by: Andrew Bowers andrewx.bowers@intel.com Signed-off-by: Jeff Kirsher jeffrey.t.kirsher@intel.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/intel/i40e/i40e_main.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/intel/i40e/i40e_main.c +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c @@ -1553,11 +1553,18 @@ static int i40e_set_mac(struct net_devic else netdev_info(netdev, "set new mac address %pM\n", addr->sa_data);

+ /* Copy the address first, so that we avoid a possible race with + * .set_rx_mode(). If we copy after changing the address in the filter + * list, we might open ourselves to a narrow race window where + * .set_rx_mode could delete our dev_addr filter and prevent traffic + * from passing. + */ + ether_addr_copy(netdev->dev_addr, addr->sa_data); + spin_lock_bh(&vsi->mac_filter_hash_lock); i40e_del_mac_filter(vsi, netdev->dev_addr); i40e_add_mac_filter(vsi, addr->sa_data); spin_unlock_bh(&vsi->mac_filter_hash_lock); - ether_addr_copy(netdev->dev_addr, addr->sa_data); if (vsi->type == I40E_VSI_MAIN) { i40e_status ret;

@@ -1739,6 +1746,14 @@ static int i40e_addr_unsync(struct net_d struct i40e_netdev_priv *np = netdev_priv(netdev); struct i40e_vsi *vsi = np->vsi;

+ /* Under some circumstances, we might receive a request to delete + * our own device address from our uc list. Because we store the + * device address in the VSI's MAC/VLAN filter list, we need to ignore + * such requests and not delete our device address from this list. + */ + if (ether_addr_equal(addr, netdev->dev_addr)) + return 0; + i40e_del_mac_filter(vsi, addr);

return 0;

Patches currently in stable-queue which might be from jacob.e.keller@intel.com are

queue-4.14/i40e-don-t-remove-netdev-dev_addr-when-syncing-uc-list.patch