linux-cve-announce - CVE-2022-50005: nfc: pn533: Fix use-after-free bugs caused by pn532_cmd

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Message-ID: <2025061829-CVE-2022-50005-fd4b@gregkh>
Date: Wed, 18 Jun 2025 13:01:10 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50005: nfc: pn533: Fix use-after-free bugs caused by pn532_cmd_timeout

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

nfc: pn533: Fix use-after-free bugs caused by pn532_cmd_timeout

When the pn532 uart device is detaching, the pn532_uart_remove()
is called. But there are no functions in pn532_uart_remove() that
could delete the cmd_timeout timer, which will cause use-after-free
bugs. The process is shown below:

    (thread 1)                  |        (thread 2)
                                |  pn532_uart_send_frame
pn532_uart_remove               |    mod_timer(&pn532->cmd_timeout,...)
  ...                           |    (wait a time)
  kfree(pn532) //FREE           |    pn532_cmd_timeout
                                |      pn532_uart_send_frame
                                |        pn532->... //USE

This patch adds del_timer_sync() in pn532_uart_remove() in order to
prevent the use-after-free bugs. What's more, the pn53x_unregister_nfc()
is well synchronized, it sets nfc_dev->shutting_down to true and there
are no syscalls could restart the cmd_timeout timer.

The Linux kernel CVE team has assigned CVE-2022-50005 to this issue.


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

	Issue introduced in 5.5 with commit c656aa4c27b17a8c70da223ed5ab42145800d6b5 and fixed in 5.10.140 with commit 50403ee6daddf0d7a14e9d3b51a377c39a08ec8c
	Issue introduced in 5.5 with commit c656aa4c27b17a8c70da223ed5ab42145800d6b5 and fixed in 5.15.64 with commit 9c34c33893db7a80d0e4b55c23d3b65e29609cfb
	Issue introduced in 5.5 with commit c656aa4c27b17a8c70da223ed5ab42145800d6b5 and fixed in 5.19.6 with commit 2c71f5d55a86fd5969428abf525c1ae6b1c7b0f5
	Issue introduced in 5.5 with commit c656aa4c27b17a8c70da223ed5ab42145800d6b5 and fixed in 6.0 with commit f1e941dbf80a9b8bab0bffbc4cbe41cc7f4c6fb6

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-2022-50005
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/nfc/pn533/uart.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/50403ee6daddf0d7a14e9d3b51a377c39a08ec8c
	https://git.kernel.org/stable/c/9c34c33893db7a80d0e4b55c23d3b65e29609cfb
	https://git.kernel.org/stable/c/2c71f5d55a86fd5969428abf525c1ae6b1c7b0f5
	https://git.kernel.org/stable/c/f1e941dbf80a9b8bab0bffbc4cbe41cc7f4c6fb6