powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.
nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel
crash when invoked during real mode interrupt handling (e.g. early HMI/MCE
interrupt handler) if percpu allocation comes from vmalloc area.
Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI()
wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when
percpu allocation is from the embedded first chunk. However with
CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu
allocation can come from the vmalloc area.
With kernel command line "percpu_alloc=page" we can force percpu allocation
to come from vmalloc area and can see kernel crash in machine_check_early:
[ 1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110
[ 1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0
[ 1.215719] --- interrupt: 200
[ 1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable)
[ 1.215722] [c000000fffd731b0] [0000000000000000] 0x0
[ 1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8
Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu
first chunk is not embedded.
Metrics
Affected Vendors & Products
Tue, 05 Nov 2024 10:15:00 +0000
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ssvc
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Fri, 25 Oct 2024 15:00:00 +0000
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Weaknesses | CWE-827 | |
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cvssV3_1
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cvssV3_1
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Thu, 12 Sep 2024 08:30:00 +0000
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ssvc
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Wed, 11 Sep 2024 13:30:00 +0000
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ssvc
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Mon, 19 Aug 2024 04:45:00 +0000
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References |
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-05-21T09:12:58.986Z
Reserved: 2024-07-29T15:50:41.179Z
Link: CVE-2024-42126

Updated: 2024-08-02T04:54:32.570Z

Status : Awaiting Analysis
Published: 2024-07-30T08:15:04.743
Modified: 2024-11-21T09:33:39.437
Link: CVE-2024-42126


Updated: 2025-07-13T11:15:05Z