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

Official 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/76390ac0bca7e5058b7482eb4d951c3bda5df812
• https://git.kernel.org/stable/c/c0071ee496e1228976c72b096f529503222708a0
• https://git.kernel.org/stable/c/7efa1a1953cd6b20b23a3524d5b4b81789c6ef25