linux-cve-announce - CVE-2022-49059: nfc: nci: add flush

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Message-ID: <2025022653-CVE-2022-49059-4608@gregkh>
Date: Wed, 26 Feb 2025 02:54:24 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2022-49059: nfc: nci: add flush_workqueue to prevent uaf

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

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

nfc: nci: add flush_workqueue to prevent uaf

Our detector found a concurrent use-after-free bug when detaching an
NCI device. The main reason for this bug is the unexpected scheduling
between the used delayed mechanism (timer and workqueue).

The race can be demonstrated below:

Thread-1                           Thread-2
                                 | nci_dev_up()
                                 |   nci_open_device()
                                 |     __nci_request(nci_reset_req)
                                 |       nci_send_cmd
                                 |         queue_work(cmd_work)
nci_unregister_device()          |
  nci_close_device()             | ...
    del_timer_sync(cmd_timer)[1] |
...                              | Worker
nci_free_device()                | nci_cmd_work()
  kfree(ndev)[3]                 |   mod_timer(cmd_timer)[2]

In short, the cleanup routine thought that the cmd_timer has already
been detached by [1] but the mod_timer can re-attach the timer [2], even
it is already released [3], resulting in UAF.

This UAF is easy to trigger, crash trace by POC is like below

[   66.703713] ==================================================================
[   66.703974] BUG: KASAN: use-after-free in enqueue_timer+0x448/0x490
[   66.703974] Write of size 8 at addr ffff888009fb7058 by task kworker/u4:1/33
[   66.703974]
[   66.703974] CPU: 1 PID: 33 Comm: kworker/u4:1 Not tainted 5.18.0-rc2 #5
[   66.703974] Workqueue: nfc2_nci_cmd_wq nci_cmd_work
[   66.703974] Call Trace:
[   66.703974]  <TASK>
[   66.703974]  dump_stack_lvl+0x57/0x7d
[   66.703974]  print_report.cold+0x5e/0x5db
[   66.703974]  ? enqueue_timer+0x448/0x490
[   66.703974]  kasan_report+0xbe/0x1c0
[   66.703974]  ? enqueue_timer+0x448/0x490
[   66.703974]  enqueue_timer+0x448/0x490
[   66.703974]  __mod_timer+0x5e6/0xb80
[   66.703974]  ? mark_held_locks+0x9e/0xe0
[   66.703974]  ? try_to_del_timer_sync+0xf0/0xf0
[   66.703974]  ? lockdep_hardirqs_on_prepare+0x17b/0x410
[   66.703974]  ? queue_work_on+0x61/0x80
[   66.703974]  ? lockdep_hardirqs_on+0xbf/0x130
[   66.703974]  process_one_work+0x8bb/0x1510
[   66.703974]  ? lockdep_hardirqs_on_prepare+0x410/0x410
[   66.703974]  ? pwq_dec_nr_in_flight+0x230/0x230
[   66.703974]  ? rwlock_bug.part.0+0x90/0x90
[   66.703974]  ? _raw_spin_lock_irq+0x41/0x50
[   66.703974]  worker_thread+0x575/0x1190
[   66.703974]  ? process_one_work+0x1510/0x1510
[   66.703974]  kthread+0x2a0/0x340
[   66.703974]  ? kthread_complete_and_exit+0x20/0x20
[   66.703974]  ret_from_fork+0x22/0x30
[   66.703974]  </TASK>
[   66.703974]
[   66.703974] Allocated by task 267:
[   66.703974]  kasan_save_stack+0x1e/0x40
[   66.703974]  __kasan_kmalloc+0x81/0xa0
[   66.703974]  nci_allocate_device+0xd3/0x390
[   66.703974]  nfcmrvl_nci_register_dev+0x183/0x2c0
[   66.703974]  nfcmrvl_nci_uart_open+0xf2/0x1dd
[   66.703974]  nci_uart_tty_ioctl+0x2c3/0x4a0
[   66.703974]  tty_ioctl+0x764/0x1310
[   66.703974]  __x64_sys_ioctl+0x122/0x190
[   66.703974]  do_syscall_64+0x3b/0x90
[   66.703974]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   66.703974]
[   66.703974] Freed by task 406:
[   66.703974]  kasan_save_stack+0x1e/0x40
[   66.703974]  kasan_set_track+0x21/0x30
[   66.703974]  kasan_set_free_info+0x20/0x30
[   66.703974]  __kasan_slab_free+0x108/0x170
[   66.703974]  kfree+0xb0/0x330
[   66.703974]  nfcmrvl_nci_unregister_dev+0x90/0xd0
[   66.703974]  nci_uart_tty_close+0xdf/0x180
[   66.703974]  tty_ldisc_kill+0x73/0x110
[   66.703974]  tty_ldisc_hangup+0x281/0x5b0
[   66.703974]  __tty_hangup.part.0+0x431/0x890
[   66.703974]  tty_release+0x3a8/0xc80
[   66.703974]  __fput+0x1f0/0x8c0
[   66.703974]  task_work_run+0xc9/0x170
[   66.703974]  exit_to_user_mode_prepare+0x194/0x1a0
[   66.703974]  syscall_exit_to_user_mode+0x19/0x50
[   66.703974]  do_syscall_64+0x48/0x90
[   66.703974]  entry_SYSCALL_64_after_hwframe+0x44/0xae

To fix the UAF, this patch adds flush_workqueue() to ensure the
nci_cmd_work is finished before the following del_timer_sync.
This combination will promise the timer is actually detached.

The Linux kernel CVE team has assigned CVE-2022-49059 to this issue.


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

	Issue introduced in 3.2 with commit 6a2968aaf50c7a22fced77a5e24aa636281efca8 and fixed in 4.9.311 with commit 7d3232214ca4ea8f7d18df264c3b254aa8089d7f
	Issue introduced in 3.2 with commit 6a2968aaf50c7a22fced77a5e24aa636281efca8 and fixed in 4.14.276 with commit 9d243aff5f7e6b04e907c617426bbdf26e996ac8
	Issue introduced in 3.2 with commit 6a2968aaf50c7a22fced77a5e24aa636281efca8 and fixed in 4.19.239 with commit 1a1748d0dd0f0a98535c6baeef671c8722107639
	Issue introduced in 3.2 with commit 6a2968aaf50c7a22fced77a5e24aa636281efca8 and fixed in 5.4.190 with commit 5c63ad2b0a267a524c12c88acb1ba9c2d109a801
	Issue introduced in 3.2 with commit 6a2968aaf50c7a22fced77a5e24aa636281efca8 and fixed in 5.10.112 with commit 67677050cecbe0edfdd81cd508415e9636ba7c65
	Issue introduced in 3.2 with commit 6a2968aaf50c7a22fced77a5e24aa636281efca8 and fixed in 5.15.35 with commit 9ded5ae40f4fe37fcc28f36d76bf45df20be5432
	Issue introduced in 3.2 with commit 6a2968aaf50c7a22fced77a5e24aa636281efca8 and fixed in 5.17.4 with commit edd4600120641e1714e30112e69a548cfb68e067
	Issue introduced in 3.2 with commit 6a2968aaf50c7a22fced77a5e24aa636281efca8 and fixed in 5.18 with commit ef27324e2cb7bb24542d6cb2571740eefe6b00dc

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-2022-49059
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:
	net/nfc/nci/core.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/7d3232214ca4ea8f7d18df264c3b254aa8089d7f
	https://git.kernel.org/stable/c/9d243aff5f7e6b04e907c617426bbdf26e996ac8
	https://git.kernel.org/stable/c/1a1748d0dd0f0a98535c6baeef671c8722107639
	https://git.kernel.org/stable/c/5c63ad2b0a267a524c12c88acb1ba9c2d109a801
	https://git.kernel.org/stable/c/67677050cecbe0edfdd81cd508415e9636ba7c65
	https://git.kernel.org/stable/c/9ded5ae40f4fe37fcc28f36d76bf45df20be5432
	https://git.kernel.org/stable/c/edd4600120641e1714e30112e69a548cfb68e067
	https://git.kernel.org/stable/c/ef27324e2cb7bb24542d6cb2571740eefe6b00dc