linux-cve-announce - CVE-2022-50453: gpiolib: cdev: fix NULL-pointer dereferences

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Message-ID: <2025100117-CVE-2022-50453-204a@gregkh>
Date: Wed,  1 Oct 2025 13:45:23 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50453: gpiolib: cdev: fix NULL-pointer dereferences

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

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

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

gpiolib: cdev: fix NULL-pointer dereferences

There are several places where we can crash the kernel by requesting
lines, unbinding the GPIO device, then calling any of the system calls
relevant to the GPIO character device's annonymous file descriptors:
ioctl(), read(), poll().

While I observed it with the GPIO simulator, it will also happen for any
of the GPIO devices that can be hot-unplugged - for instance any HID GPIO
expander (e.g. CP2112).

This affects both v1 and v2 uAPI.

This fixes it partially by checking if gdev->chip is not NULL but it
doesn't entirely remedy the situation as we still have a race condition
in which another thread can remove the device after the check.

The Linux kernel CVE team has assigned CVE-2022-50453 to this issue.


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

	Issue introduced in 4.8 with commit d7c51b47ac11e66f547b55640405c1c474642d72 and fixed in 5.10.163 with commit 6d79546622baab843172b52c3af035f83c1b21df
	Issue introduced in 4.8 with commit d7c51b47ac11e66f547b55640405c1c474642d72 and fixed in 5.15.86 with commit 7c755a2d6df511eeb5afba966ac28140f9ea5063
	Issue introduced in 4.8 with commit d7c51b47ac11e66f547b55640405c1c474642d72 and fixed in 6.0.16 with commit d66f68ac9e7ba46b6b90fbe25155723f2126088a
	Issue introduced in 4.8 with commit d7c51b47ac11e66f547b55640405c1c474642d72 and fixed in 6.1.2 with commit ac6ce3cd7a3e10a2e37b8970bab81b4d33d5cfc3
	Issue introduced in 4.8 with commit d7c51b47ac11e66f547b55640405c1c474642d72 and fixed in 6.2 with commit 533aae7c94dbc2b14301cfd68ae7e0e90f0c8438

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-2022-50453
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/gpio/gpiolib-cdev.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/6d79546622baab843172b52c3af035f83c1b21df
	https://git.kernel.org/stable/c/7c755a2d6df511eeb5afba966ac28140f9ea5063
	https://git.kernel.org/stable/c/d66f68ac9e7ba46b6b90fbe25155723f2126088a
	https://git.kernel.org/stable/c/ac6ce3cd7a3e10a2e37b8970bab81b4d33d5cfc3
	https://git.kernel.org/stable/c/533aae7c94dbc2b14301cfd68ae7e0e90f0c8438