CVE-2026-64214

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> powerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise()<br /> <br /> A kernel panic is observed when handling machine check exceptions from<br /> real mode.<br /> <br /> BUG: Unable to handle kernel data access on read at 0xc00000006be21300<br /> Oops: Kernel access of bad area, sig: 11 [#1]<br /> MSR: 8000000000001003 CR: 88222248 XER: 00000005<br /> CFAR: c00000000003ffc4 DAR: c00000006be21300 DSISR: 40000000 IRQMASK: 0<br /> NIP [c000000000029e40] arch_irq_work_raise+0x10/0x70<br /> LR [c00000000003ffc8] machine_check_queue_event+0xa8/0x150<br /> Call Trace:<br /> [c0000000179d3c70] [c00000000003ff64] machine_check_queue_event+0x44/0x150<br /> [c0000000179d3d30] [c0000000000084e0] machine_check_early_common+0x1f0/0x2c0<br /> <br /> The crash occurs because arch_irq_work_raise() calls preempt_disable()<br /> from machine check exception (MCE) handlers running in real mode. In<br /> this context, accessing the preempt_count can fault, leading to the panic.<br /> <br /> The preempt_disable()/preempt_enable() pair in arch_irq_work_raise()<br /> was originally added by commit 0fe1ac48bef0 ("powerpc/perf_event: Fix<br /> oops due to perf_event_do_pending call") to avoid races while raising<br /> irq work from exception context.<br /> <br /> Later, commit 471ba0e686cb ("irq_work: Do not raise an IPI when<br /> queueing work on the local CPU") added preemption protection in<br /> irq_work_queue() path, while commit 20b876918c06 ("irq_work: Use per<br /> cpu atomics instead of regular atomics") added equivalent<br /> protection in irq_work_queue_on() before reaching arch_irq_work_raise():<br /> <br /> irq_work_queue() / irq_work_queue_on()<br /> -&gt; preempt_disable()<br /> -&gt; __irq_work_queue_local()<br /> -&gt; irq_work_raise()<br /> -&gt; arch_irq_work_raise()<br /> <br /> As a result, callers other than mce_irq_work_raise() already execute<br /> with preemption disabled, making the additional<br /> preempt_disable()/preempt_enable() pair in arch_irq_work_raise()<br /> redundant.<br /> <br /> The arch_irq_work_raise() function executes in NMI context when called<br /> from MCE handler. Hence we will not be preempted or scheduled out since<br /> we are in NMI context with MSR[EE]=0. Therefore, it is safe to remove<br /> the preempt_disable()/preempt_enable() calls from here.<br /> <br /> Remove it to avoid accessing preempt_count from real mode context.<br /> <br /> [Maddy: Fixed the commit title]