CVE-2026-89769: clocksource/drivers/nxp-pit: Fix IRQ leak on cpuhp_setup_state error path

CVE-2026-89769: clocksource/drivers/nxp-pit: Fix IRQ leak on cpuhp_setup_state error path

[Greg Kroah-Hartman]

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

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

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

clocksource/drivers/nxp-pit: Fix IRQ leak on cpuhp_setup_state error path

When cpuhp_setup_state fails after pit_clockevent_per_cpu_init has
successfully called request_irq, the error handling jumps directly to
out_pit_clocksource_unregister without freeing the registered IRQ.

This leaks the IRQ line and, since kfree(pit) follows, leaves a
dangling pointer registered as the interrupt handler's dev_id,
potentially leading to a use-after-free if the IRQ fires afterwards.

Fix it by calling pit_clockevent_per_cpu_exit to properly release the
IRQ before falling through to the existing cleanup chain.

The Linux kernel CVE team has assigned CVE-2026-89769 to this issue.


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

	Issue introduced in 6.18 with commit bee33f22d7c30626e711b4900e3f460b6e0e104f and fixed in 6.18.50 with commit d53c29a89a15e56a1797f3ef249955e544782e04
	Issue introduced in 6.18 with commit bee33f22d7c30626e711b4900e3f460b6e0e104f and fixed in 7.2.4 with commit cdcd861123248e871c2ec2be968b0a1b2a5a34b0
	Issue introduced in 6.18 with commit bee33f22d7c30626e711b4900e3f460b6e0e104f and fixed in 7.3-rc1 with commit 05520e035f8332c8e33f3011b5ca016fde61793d

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-2026-89769
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/clocksource/timer-nxp-pit.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/d53c29a89a15e56a1797f3ef249955e544782e04
	https://git.kernel.org/stable/c/cdcd861123248e871c2ec2be968b0a1b2a5a34b0
	https://git.kernel.org/stable/c/05520e035f8332c8e33f3011b5ca016fde61793d