Subject: CVE-2022-48842: ice: Fix race condition during interface enslave

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

ice: Fix race condition during interface enslave

Commit 5dbbbd01cbba83 ("ice: Avoid RTNL lock when re-creating
auxiliary device") changes a process of re-creation of aux device
so ice_plug_aux_dev() is called from ice_service_task() context.
This unfortunately opens a race window that can result in dead-lock
when interface has left LAG and immediately enters LAG again.

Reproducer:
```
#!/bin/sh

ip link add lag0 type bond mode 1 miimon 100
ip link set lag0

for n in {1..10}; do
        echo Cycle: $n
        ip link set ens7f0 master lag0
        sleep 1
        ip link set ens7f0 nomaster
done
```

This results in:
[20976.208697] Workqueue: ice ice_service_task [ice]
[20976.213422] Call Trace:
[20976.215871]  __schedule+0x2d1/0x830
[20976.219364]  schedule+0x35/0xa0
[20976.222510]  schedule_preempt_disabled+0xa/0x10
[20976.227043]  __mutex_lock.isra.7+0x310/0x420
[20976.235071]  enum_all_gids_of_dev_cb+0x1c/0x100 [ib_core]
[20976.251215]  ib_enum_roce_netdev+0xa4/0xe0 [ib_core]
[20976.256192]  ib_cache_setup_one+0x33/0xa0 [ib_core]
[20976.261079]  ib_register_device+0x40d/0x580 [ib_core]
[20976.266139]  irdma_ib_register_device+0x129/0x250 [irdma]
[20976.281409]  irdma_probe+0x2c1/0x360 [irdma]
[20976.285691]  auxiliary_bus_probe+0x45/0x70
[20976.289790]  really_probe+0x1f2/0x480
[20976.298509]  driver_probe_device+0x49/0xc0
[20976.302609]  bus_for_each_drv+0x79/0xc0
[20976.306448]  __device_attach+0xdc/0x160
[20976.310286]  bus_probe_device+0x9d/0xb0
[20976.314128]  device_add+0x43c/0x890
[20976.321287]  __auxiliary_device_add+0x43/0x60
[20976.325644]  ice_plug_aux_dev+0xb2/0x100 [ice]
[20976.330109]  ice_service_task+0xd0c/0xed0 [ice]
[20976.342591]  process_one_work+0x1a7/0x360
[20976.350536]  worker_thread+0x30/0x390
[20976.358128]  kthread+0x10a/0x120
[20976.365547]  ret_from_fork+0x1f/0x40
...
[20976.438030] task:ip              state:D stack:    0 pid:213658 ppid:213627 flags:0x00004084
[20976.446469] Call Trace:
[20976.448921]  __schedule+0x2d1/0x830
[20976.452414]  schedule+0x35/0xa0
[20976.455559]  schedule_preempt_disabled+0xa/0x10
[20976.460090]  __mutex_lock.isra.7+0x310/0x420
[20976.464364]  device_del+0x36/0x3c0
[20976.467772]  ice_unplug_aux_dev+0x1a/0x40 [ice]
[20976.472313]  ice_lag_event_handler+0x2a2/0x520 [ice]
[20976.477288]  notifier_call_chain+0x47/0x70
[20976.481386]  __netdev_upper_dev_link+0x18b/0x280
[20976.489845]  bond_enslave+0xe05/0x1790 [bonding]
[20976.494475]  do_setlink+0x336/0xf50
[20976.502517]  __rtnl_newlink+0x529/0x8b0
[20976.543441]  rtnl_newlink+0x43/0x60
[20976.546934]  rtnetlink_rcv_msg+0x2b1/0x360
[20976.559238]  netlink_rcv_skb+0x4c/0x120
[20976.563079]  netlink_unicast+0x196/0x230
[20976.567005]  netlink_sendmsg+0x204/0x3d0
[20976.570930]  sock_sendmsg+0x4c/0x50
[20976.574423]  ____sys_sendmsg+0x1eb/0x250
[20976.586807]  ___sys_sendmsg+0x7c/0xc0
[20976.606353]  __sys_sendmsg+0x57/0xa0
[20976.609930]  do_syscall_64+0x5b/0x1a0
[20976.613598]  entry_SYSCALL_64_after_hwframe+0x65/0xca

1. Command 'ip link ... set nomaster' causes that ice_plug_aux_dev()
   is called from ice_service_task() context, aux device is created
   and associated device->lock is taken.
2. Command 'ip link ... set master...' calls ice's notifier under
   RTNL lock and that notifier calls ice_unplug_aux_dev(). That
   function tries to take aux device->lock but this is already taken
   by ice_plug_aux_dev() in step 1
3. Later ice_plug_aux_dev() tries to take RTNL lock but this is already
   taken in step 2
4. Dead-lock

The patch fixes this issue by following changes:
- Bit ICE_FLAG_PLUG_AUX_DEV is kept to be set during ice_plug_aux_dev()
  call in ice_service_task()
- The bit is checked in ice_clear_rdma_cap() and only if it is not set
  then ice_unplug_aux_dev() is called. If it is set (in other words
  plugging of aux device was requested and ice_plug_aux_dev() is
  potentially running) then the function only clears the bit
- Once ice_plug_aux_dev() call (in ice_service_task) is finished
  the bit ICE_FLAG_PLUG_AUX_DEV is cleared but it is also checked
  whether it was already cleared by ice_clear_rdma_cap(). If so then
  aux device is unplugged.

The Linux kernel CVE team has assigned CVE-2022-48842 to this issue.

Affected and fixed versions
===========================

	Fixed in 5.15.30 with commit a9bbacc53d1f
	Fixed in 5.16.16 with commit e1014fc55723
	Fixed in 5.17 with commit 5cb1ebdbc434

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-48842
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/intel/ice/ice.h
	drivers/net/ethernet/intel/ice/ice_main.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/a9bbacc53d1f5ed8febbfdf31401d20e005f49ef
	https://git.kernel.org/stable/c/e1014fc5572375658fa421531cedb6e084f477dc
	https://git.kernel.org/stable/c/5cb1ebdbc4342b1c2ce89516e19808d64417bdbc