powerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-64214
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-24 16:16:49 UTC
Updated2026-07-24 16:16:49 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: powerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise() A kernel panic is observed when handling machine check exceptions from real mode. BUG: Unable to handle kernel data access on read at 0xc00000006be21300 Oops: Kernel access of bad area, sig: 11 [#1] MSR: 8000000000001003 <SF,ME,RI,LE> CR: 88222248 XER: 00000005 CFAR: c00000000003ffc4 DAR: c00000006be21300 DSISR: 40000000 IRQMASK: 0 NIP [c000000000029e40] arch_irq_work_raise+0x10/0x70 LR [c00000000003ffc8] machine_check_queue_event+0xa8/0x150 Call Trace: [c0000000179d3c70] [c00000000003ff64] machine_check_queue_event+0x44/0x150 [c0000000179d3d30] [c0000000000084e0] machine_check_early_common+0x1f0/0x2c0 The crash occurs because arch_irq_work_raise() calls preempt_disable() from machine check exception (MCE) handlers running in real mode. In this context, accessing the preempt_count can fault, leading to the panic. The preempt_disable()/preempt_enable() pair in arch_irq_work_raise() was originally added by commit 0fe1ac48bef0 ("powerpc/perf_event: Fix oops due to perf_event_do_pending call") to avoid races while raising irq work from exception context. Later, commit 471ba0e686cb ("irq_work: Do not raise an IPI when queueing work on the local CPU") added preemption protection in irq_work_queue() path, while commit 20b876918c06 ("irq_work: Use per cpu atomics instead of regular atomics") added equivalent protection in irq_work_queue_on() before reaching arch_irq_work_raise(): irq_work_queue() / irq_work_queue_on() -> preempt_disable() -> __irq_work_queue_local() -> irq_work_raise() -> arch_irq_work_raise() As a result, callers other than mce_irq_work_raise() already execute with preemption disabled, making the additional preempt_disable()/preempt_enable() pair in arch_irq_work_raise() redundant. The arch_irq_work_raise() function executes in NMI context when called from MCE handler. Hence we will not be preempted or scheduled out since we are in NMI context with MSR[EE]=0. Therefore, it is safe to remove the preempt_disable()/preempt_enable() calls from here. Remove it to avoid accessing preempt_count from real mode context. [Maddy: Fixed the commit title]

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected cc15ff3275694fedc33cd3d53212a43eec7aa0bc 51860e423592893cd7bfa7287d99a3aff4dc3a9d git Not specified
CNA Linux Linux affected cc15ff3275694fedc33cd3d53212a43eec7aa0bc a09d07ac45e283c9861a9ceea06f56d0ba851d22 git Not specified
CNA Linux Linux affected cc15ff3275694fedc33cd3d53212a43eec7aa0bc 72d8d1c36452a4d3ee134b1da48de7518c1329f9 git Not specified
CNA Linux Linux affected cc15ff3275694fedc33cd3d53212a43eec7aa0bc 6dcd072a5ae3aed336e4a67a7d4cc5205b240065 git Not specified
CNA Linux Linux affected cc15ff3275694fedc33cd3d53212a43eec7aa0bc 8079acc5ee5235a627e4586d4f42082a9000ea64 git Not specified
CNA Linux Linux affected cc15ff3275694fedc33cd3d53212a43eec7aa0bc 31467b23823ffec1f6fff407f8e3ca9af8b7491a git Not specified
CNA Linux Linux affected 5.18 Not specified
CNA Linux Linux unaffected 5.18 semver Not specified
CNA Linux Linux unaffected 6.1.175 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.142 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.92 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.34 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.11 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/6dcd072a5ae3aed336e4a67a7d4cc5205b240065 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/72d8d1c36452a4d3ee134b1da48de7518c1329f9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/51860e423592893cd7bfa7287d99a3aff4dc3a9d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/31467b23823ffec1f6fff407f8e3ca9af8b7491a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8079acc5ee5235a627e4586d4f42082a9000ea64 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a09d07ac45e283c9861a9ceea06f56d0ba851d22 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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