CVE-2026-99189: gpio: mxc: fix race between chained IRQ handler install and probe completion

CVE-2026-99189: gpio: mxc: fix race between chained IRQ handler install and probe completion

[Greg Kroah-Hartman]

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

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

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

gpio: mxc: fix race between chained IRQ handler install and probe completion

mxc_update_irq_chained_handler() is called before the IRQ domain, the
generic IRQ chip, and the port list entry are set up. If an interrupt
arrives in that window:

 - mx3_gpio_irq_handler() calls generic_handle_domain_irq() with
   port->domain still NULL.
 - mx2_gpio_irq_handler() walks mxc_gpio_ports, but the port has not
   been added to the list yet.

Additionally, if any of the subsequent probe steps
(gpio_generic_chip_init(), devm_gpiochip_add_data(),
irq_domain_create_legacy(), or mxc_gpio_init_gc()) fail, the error
paths never unregister the chained handler, leaving a dangling handler
that points at freed memory.

Move the handler installation after all its dependencies are ready and
after list_add_tail(), so the handler is never live while the data
structures it touches are incomplete, and is never installed if probe
fails.

The Linux kernel CVE team has assigned CVE-2026-99189 to this issue.


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

	Issue introduced in 6.6 with commit 5f6d1998adeb5374ef248b5ba2e2a0c30ab0f60b and fixed in 6.18.59 with commit 261802c14e1a3281987ea8f106701e5ed9652f68
	Issue introduced in 6.6 with commit 5f6d1998adeb5374ef248b5ba2e2a0c30ab0f60b and fixed in 7.2.13 with commit 6c1e035d881579a6e4ed1ce5feabb13d23e80a82
	Issue introduced in 6.6 with commit 5f6d1998adeb5374ef248b5ba2e2a0c30ab0f60b and fixed in 7.3 with commit 38d44f78f041ffe60c8e2443b99434a199e7541d

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-2026-99189
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/gpio-mxc.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/261802c14e1a3281987ea8f106701e5ed9652f68
	https://git.kernel.org/stable/c/6c1e035d881579a6e4ed1ce5feabb13d23e80a82
	https://git.kernel.org/stable/c/38d44f78f041ffe60c8e2443b99434a199e7541d