linux-cve-announce - CVE-2023-53176: serial: 8250: Reinit port->pm on port specific driver unbind

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Message-ID: <2025091555-CVE-2023-53176-4194@gregkh>
Date: Mon, 15 Sep 2025 16:02:30 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53176: serial: 8250: Reinit port->pm on port specific driver unbind

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

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

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

serial: 8250: Reinit port->pm on port specific driver unbind

When we unbind a serial port hardware specific 8250 driver, the generic
serial8250 driver takes over the port. After that we see an oops about 10
seconds later. This can produce the following at least on some TI SoCs:

Unhandled fault: imprecise external abort (0x1406)
Internal error: : 1406 [#1] SMP ARM

Turns out that we may still have the serial port hardware specific driver
port->pm in use, and serial8250_pm() tries to call it after the port
specific driver is gone:

serial8250_pm [8250_base] from uart_change_pm+0x54/0x8c [serial_base]
uart_change_pm [serial_base] from uart_hangup+0x154/0x198 [serial_base]
uart_hangup [serial_base] from __tty_hangup.part.0+0x328/0x37c
__tty_hangup.part.0 from disassociate_ctty+0x154/0x20c
disassociate_ctty from do_exit+0x744/0xaac
do_exit from do_group_exit+0x40/0x8c
do_group_exit from __wake_up_parent+0x0/0x1c

Let's fix the issue by calling serial8250_set_defaults() in
serial8250_unregister_port(). This will set the port back to using
the serial8250 default functions, and sets the port->pm to point to
serial8250_pm.

The Linux kernel CVE team has assigned CVE-2023-53176 to this issue.


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

	Fixed in 4.14.316 with commit 490bf37eaabb0a857ed1ae8e75d8854e41662f1c
	Fixed in 4.19.284 with commit c9e080c3005fd183c56ff8f4d75edb5da0765d2c
	Fixed in 5.4.244 with commit d5cd2928d31042a7c0a01464f9a8d95be736421d
	Fixed in 5.10.181 with commit 2c86a1305c1406f45ea780d06953c484ea1d9e6e
	Fixed in 5.15.113 with commit 1ba5594739d858e524ff0f398ee1ebfe0a8b9d41
	Fixed in 6.1.30 with commit af4d6dbb1a92ea424ad1ba1d0c88c7fa2345d872
	Fixed in 6.3.4 with commit 8e596aed5f2f98cf3e6e98d6fe1d689f4a319308
	Fixed in 6.4 with commit 04e82793f068d2f0ffe62fcea03d007a8cdc16a7

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-2023-53176
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/tty/serial/8250/8250_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/490bf37eaabb0a857ed1ae8e75d8854e41662f1c
	https://git.kernel.org/stable/c/c9e080c3005fd183c56ff8f4d75edb5da0765d2c
	https://git.kernel.org/stable/c/d5cd2928d31042a7c0a01464f9a8d95be736421d
	https://git.kernel.org/stable/c/2c86a1305c1406f45ea780d06953c484ea1d9e6e
	https://git.kernel.org/stable/c/1ba5594739d858e524ff0f398ee1ebfe0a8b9d41
	https://git.kernel.org/stable/c/af4d6dbb1a92ea424ad1ba1d0c88c7fa2345d872
	https://git.kernel.org/stable/c/8e596aed5f2f98cf3e6e98d6fe1d689f4a319308
	https://git.kernel.org/stable/c/04e82793f068d2f0ffe62fcea03d007a8cdc16a7