Re: [PATCH] vlan: fix potential race in vlan_cleanup_module vs vlan_ioctl_handler

[Patrick McHardy]

Pavel Emelyanov wrote:

The vlan module cleanup function starts with

        vlan_netlink_fini();
        vlan_ioctl_set(NULL);

The first call removes all the vlan devices and
the second one closes the vlan ioctl.

AFAIS there's a tiny race window between these two

calls - after rtnl unregistered all the vlans, but the ioctl handler isn't set to NULL yet, user can manage to call this ioctl and create one vlan device, and that this function will later BUG_ON seeing non-emply hashes.

Indeed, I can't see anything preventing this.

I think, that we must first close the vlan ioctl
and only after this remove all the vlans with the
vlan_netlink_fini() call.

That looks correct, thanks Pavel. Dave, please apply.

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