CVE-2026-89589

A flaw was found in the ACPI/APEI/GHES component of the Linux kernel. Incorrect usage of spinlocks in the CXL CPER work registration and unregistration helpers can lead to a deadlock. If a CPU holds a lock while a GHES interrupt arrives on the same CPU, the interrupt handler will spin on the held lock, causing the system to become unresponsive. This can result in a denial of service.

A MODERATE severity denial-of-service flaw was found in the ACPI/APEI/GHES error-handling code of the Linux kernel. The CXL CPER work registration and unregistration helpers acquire their locks with local interrupts enabled, while the corresponding event-posting paths execute in hard IRQ context and take the same locks with interrupts saved. If a GHES error-notification interrupt arrives on a CPU that is holding one of these locks, the interrupt handler spins waiting for the lock to be released while the holder has been preempted by that same interrupt, deadlocking the CPU and leaving the system unresponsive. On PREEMPT_RT kernels the issue is aggravated because spinlock_t is backed by a sleeping rt_mutex, which must not be acquired from hard IRQ context.

The affected Red Hat offerings are Red Hat Enterprise Linux 9 and 10 (kernel and kernel-rt), OpenShift Container Platform 4.19 and later, and Red Hat In-Vehicle OS 2, all of which contain the vulnerable code. The fix is currently deferred for these streams, so the residual risk remains until a future update addresses it. The practical risk is limited: the deadlock is a timing-dependent race that requires a CXL-related GHES hardware error notification to arrive on a CPU while the lock is held, and the consequence is a system hang affecting availability only, with no impact on confidentiality or integrity. Red Hat Enterprise Linux 7 and 8, RHEL 9.2 and 9.4, and OpenShift Container Platform 4.12 through 4.18 are not affected because the vulnerable code is not present in their kernels.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.