This is a note to let you know that I've just added the patch titled
ethtool: do not perform operations on net devices being unregistered
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ethtool-do-not-perform-operations-on-net-devices-being-unregistered.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From dde91ccfa25fd58f64c397d91b81a4b393100ffa Mon Sep 17 00:00:00 2001
From: Antoine Tenart <atenart@xxxxxxxxxx>
Date: Fri, 3 Dec 2021 11:13:18 +0100
Subject: ethtool: do not perform operations on net devices being unregistered
From: Antoine Tenart <atenart@xxxxxxxxxx>
commit dde91ccfa25fd58f64c397d91b81a4b393100ffa upstream.
There is a short period between a net device starts to be unregistered
and when it is actually gone. In that time frame ethtool operations
could still be performed, which might end up in unwanted or undefined
behaviours[1].
Do not allow ethtool operations after a net device starts its
unregistration. This patch targets the netlink part as the ioctl one
isn't affected: the reference to the net device is taken and the
operation is executed within an rtnl lock section and the net device
won't be found after unregister.
[1] For example adding Tx queues after unregister ends up in NULL
pointer exceptions and UaFs, such as:
BUG: KASAN: use-after-free in kobject_get+0x14/0x90
Read of size 1 at addr ffff88801961248c by task ethtool/755
CPU: 0 PID: 755 Comm: ethtool Not tainted 5.15.0-rc6+ #778
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/014
Call Trace:
dump_stack_lvl+0x57/0x72
print_address_description.constprop.0+0x1f/0x140
kasan_report.cold+0x7f/0x11b
kobject_get+0x14/0x90
kobject_add_internal+0x3d1/0x450
kobject_init_and_add+0xba/0xf0
netdev_queue_update_kobjects+0xcf/0x200
netif_set_real_num_tx_queues+0xb4/0x310
veth_set_channels+0x1c3/0x550
ethnl_set_channels+0x524/0x610
Fixes: 041b1c5d4a53 ("ethtool: helper functions for netlink interface")
Suggested-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Antoine Tenart <atenart@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20211203101318.435618-1-atenart@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ethtool/netlink.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/ethtool/netlink.c
+++ b/net/ethtool/netlink.c
@@ -40,7 +40,8 @@ int ethnl_ops_begin(struct net_device *d
if (dev->dev.parent)
pm_runtime_get_sync(dev->dev.parent);
- if (!netif_device_present(dev)) {
+ if (!netif_device_present(dev) ||
+ dev->reg_state == NETREG_UNREGISTERING) {
ret = -ENODEV;
goto err;
}
Patches currently in stable-queue which might be from atenart@xxxxxxxxxx are
queue-5.15/ethtool-do-not-perform-operations-on-net-devices-being-unregistered.patch
