The SCH GPIO driver in the Linux kernel incorrectly acquires a sleeping‑capable spinlock during the interrupt startup sequence. When the kernel is built with PREEMPT_RT, this lock is treated as a sleeping lock, but the context in which it is used is non‑sleepable. This mismatch triggers a lockdep violation and can lead to a deadlock, kernel panic, or system freeze, thereby disrupting availability.

Any system running a Linux kernel that compiles the SCH GPIO driver remains vulnerable. This includes all Unix‑like systems whose kernels use the legacy spinlock for sch_irq_unmask() and sch_irq_mask_unmask(), especially those distributed with PREEMPT_RT support. No specific kernel versions are listed in the advisory, so the vulnerability persists until the lock is converted to raw_spinlock_t.

The CVSS score of 5.5 indicates a moderate level of risk, while the EPSS score is less than 1 % and the vulnerability is not listed in the CISA KEV catalog, indicating a low probability of exploitation. The flaw manifests only when an interrupt is initialized under a PREEMPT_RT build and the sleeping lock is invoked from a non‑sleepable context. Based on the description, it is inferred that an attacker would need privileged access—such as root or the ability to trigger an interrupt during kernel initialization—to create the unsafe state. The impact is limited to system availability and does not expose confidential data or allow remote code execution.