CVE-2026-74468

Received Received - Intake

Raw Spinlock Fix in Linux Kernel GPIO PCH Driver

Publication date: 2026-08-15

Last updated on: 2026-08-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: gpio: pch: use raw_spinlock_t for the register lock pch_irq_type() is registered as the irq_chip .irq_set_type callback and takes chip->spinlock with spin_lock_irqsave(). This callback is reached from __setup_irq() -> __irq_set_trigger() -> chip->irq_set_type() while the caller holds desc->lock, a raw_spinlock_t, with hardirqs disabled. That context is not sleepable, but on PREEMPT_RT a regular spinlock_t is an rtmutex-backed sleeping lock, so acquiring it there is invalid. This was confirmed on a PREEMPT_RT kernel with lockdep (PROVE_RAW_LOCK_NESTING and DEBUG_ATOMIC_SLEEP). A grounded PoC mirrored pch_irq_type()'s locking and drove it through the real genirq carrier irq_set_irq_type() -> __irq_set_trigger() -> chip->irq_set_type(), i.e. the same __irq_set_trigger() edge that __setup_irq() takes for a requested IRQ. With the original spin_lock_irqsave() edge lockdep reported an invalid wait context, immediately followed by: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 95, name: insmod hardirqs last disabled at (3784): _raw_spin_lock_irqsave+0x4f/0x60 rt_spin_lock+0x3a/0x1c0 repro_irq_set_type+0x64/0xa0 [pch_repro] __irq_set_trigger+0x69/0x140 irq_set_irq_type+0x78/0xd0 Switching the mirrored lock to raw_spinlock_t made both splats go away. Convert the register lock to raw_spinlock_t. The same lock also serializes the GPIO direction/value callbacks and the suspend/resume register save/restore, but all of those critical sections only perform MMIO register accesses (ioread32()/iowrite32()) and irq_set_handler_locked(); none of them contain sleepable operations. Keeping this register lock non-sleeping is therefore appropriate for the irqchip callbacks and does not change the GPIO-side locking contract. This is the same class of issue and fix as recently addressed for other GPIO controllers, e.g. commit 286533cb14a3 ("gpio: sch: use raw_spinlock_t in the irq startup path") and commit 90f0109019e6 ("gpio: eic-sprd: use raw_spinlock_t in the irq startup path").

CVSS Scores

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Meta Information

Published

2026-08-15

Last Modified

2026-08-19

Generated

2026-09-04

AI Q&A

2026-08-15

EPSS Evaluated

2026-09-03

NVD

CVE-2026-74468

EUVD

EUVD-2026-59661

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a locking issue in the GPIO subsystem. The pch_irq_type() function, used as an interrupt handler, incorrectly uses a regular spinlock_t while holding a raw_spinlock_t in a non-sleepable context. On PREEMPT_RT kernels, regular spinlocks can sleep, causing invalid wait context errors and potential system crashes.

Detection Guidance

This vulnerability is specific to the Linux kernel's GPIO subsystem and is related to improper lock handling in the pch_irq_type() function. Detection requires checking the kernel version and the presence of the affected GPIO driver. Use commands like 'uname -a' to check the kernel version and 'lsmod | grep pch' to see if the pch_gpio module is loaded. If the module is loaded and the kernel is vulnerable, lockdep may report issues during IRQ handling.

Impact Analysis

This vulnerability can cause system instability or crashes on Linux systems using PREEMPT_RT kernels with affected GPIO controllers. It may lead to kernel panics or unexpected behavior during interrupt handling, particularly when managing GPIO interrupts.

Compliance Impact

This vulnerability does not directly affect compliance with standards like GDPR or HIPAA. It is a low-level Linux kernel locking issue in the GPIO subsystem that could cause system instability or crashes under specific real-time kernel configurations (PREEMPT_RT). No data exposure or privacy implications are described.

Mitigation Strategies

Apply the kernel patch that converts the register lock to raw_spinlock_t. Update to a kernel version that includes the fix. If updating is not immediately possible, disable the pch_gpio driver if not in use. Monitor for lockdep warnings or kernel crashes related to IRQ handling.

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