CVE-2026-99050: gpio: mpsse: fix race when arming the IRQ poll worker

CVE-2026-99050: gpio: mpsse: fix race when arming the IRQ poll worker

[Greg Kroah-Hartman]

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

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

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

gpio: mpsse: fix race when arming the IRQ poll worker

gpio_mpsse_irq_enable() arms the poll worker before publishing it:
schedule_work() runs before the worker is added to priv->workers. If
gpio_mpsse_disconnect() walks the list in that window it misses the
worker, and once disconnect returns, the USB core frees mpsse_priv
while the orphaned gpio_mpsse_poll() work keeps accessing it, causing
a use-after-free.

Fix this by publishing and arming the worker in one irq_spin
critical section. Teardown walks the same list under irq_spin, so a
worker found on the list is guaranteed to be armed, and
cancel_work_sync() handles it whether it is queued or running.

A worker armed after the disconnect walk would still be missed, so
also set a new priv->dying flag under irq_spin before the teardown
walk, and check it in the same critical section, freeing it via
kfree_rcu() instead when the device is going away, since kfree()
would be called with the IRQ core's raw spinlock held and may sleep
on PREEMPT_RT. schedule_work() is safe to call with irq_spin held,
and the next probe gets a fresh mpsse_priv, so the flag never needs
to be cleared.

This issue was found by an in-house static analysis tool.

The Linux kernel CVE team has assigned CVE-2026-99050 to this issue.


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

	Issue introduced in 6.18.6 with commit 472d900c8bcac301ae0e40fdca7db799bd989ff5 and fixed in 6.18.57 with commit 76390ac0bca7e5058b7482eb4d951c3bda5df812
	Issue introduced in 6.19 with commit 179ef1127d7a4f09f0e741fa9f30b8a8e7886271 and fixed in 7.2.11 with commit c0071ee496e1228976c72b096f529503222708a0
	Issue introduced in 6.19 with commit 179ef1127d7a4f09f0e741fa9f30b8a8e7886271 and fixed in 7.3 with commit 7efa1a1953cd6b20b23a3524d5b4b81789c6ef25

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-2026-99050
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-mpsse.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/76390ac0bca7e5058b7482eb4d951c3bda5df812
	https://git.kernel.org/stable/c/c0071ee496e1228976c72b096f529503222708a0
	https://git.kernel.org/stable/c/7efa1a1953cd6b20b23a3524d5b4b81789c6ef25