CVE-2026-93254

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

arm64: entry: Avoid unnecessary local_irq_disable() on kernel exit

Currently, when exiting to kernel mode, we attempt involuntary

preemption. The preemption logic expects IRQs to be disabled, which is

why we call local_irq_disable() before attempting preemption.

However, depending on the context, local_irq_disable() may be

unnecessary:

- __el1_irq(), the non-NMI EL1 IRQ path, already has IRQs disabled, so

local_irq_disable() is redundant.

- irqentry_exit_to_kernel_mode_preempt() immediately returns when

exiting from an NMI-like context, so calling local_irq_disable()

beforehand is unnecessary work.

Furthermore, it confuses the pNMI state tracking when we are in a

context with interrupts disabled and the GIC_PRIO_PSR_I_SET bit is set

in the PMR, leading to a warning when

CONFIG_ARM64_DEBUG_PRIORITY_MASKING=y:

WARNING: ./arch/arm64/include/asm/irqflags.h:63 at arm64_exit_to_kernel_mode+0xb8/0xc0, CPU#40: retsnoop/31805

CPU: 40 UID: 0 PID: 31805 Comm: retsnoop Not tainted 7.2.0-rc6-next-20260805 #7 PREEMPTLAZY

pstate: 234013c9 (nzCv DAIF +PAN -UAO +TCO +DIT +SSBS BTYPE=--)

pc : arm64_exit_to_kernel_mode (arch/arm64/kernel/entry-common.c:63)

lr : el1_abort (arch/arm64/kernel/entry-common.c:323)

pmr: 000000f0

Call trace:

arm64_exit_to_kernel_mode (arch/arm64/kernel/entry-common.c:63) (P)

el1_abort (arch/arm64/kernel/entry-common.c:323)

el1h_64_sync_handler (arch/arm64/kernel/entry-common.c:449)

el1h_64_sync (arch/arm64/kernel/entry.S:589)

[...]

Split arm64_exit_to_kernel_mode() into preempt, non-preempt, and

dispatch parts so that we can avoid this extra work where it is not

needed and avoid breaking the pNMI tracking logic.