FKIE_CVE-2026-64214

Vulnerability from fkie_nvd - Published: 2026-07-24 16:16 - Updated: 2026-07-30 14:59
Severity
Summary
In 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]
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/31467b23823ffec1f6fff407f8e3ca9af8b7491a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/51860e423592893cd7bfa7287d99a3aff4dc3a9d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6dcd072a5ae3aed336e4a67a7d4cc5205b240065
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/72d8d1c36452a4d3ee134b1da48de7518c1329f9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8079acc5ee5235a627e4586d4f42082a9000ea64
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a09d07ac45e283c9861a9ceea06f56d0ba851d22
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/powerpc/kernel/time.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "51860e423592893cd7bfa7287d99a3aff4dc3a9d",
              "status": "affected",
              "version": "cc15ff3275694fedc33cd3d53212a43eec7aa0bc",
              "versionType": "git"
            },
            {
              "lessThan": "a09d07ac45e283c9861a9ceea06f56d0ba851d22",
              "status": "affected",
              "version": "cc15ff3275694fedc33cd3d53212a43eec7aa0bc",
              "versionType": "git"
            },
            {
              "lessThan": "72d8d1c36452a4d3ee134b1da48de7518c1329f9",
              "status": "affected",
              "version": "cc15ff3275694fedc33cd3d53212a43eec7aa0bc",
              "versionType": "git"
            },
            {
              "lessThan": "6dcd072a5ae3aed336e4a67a7d4cc5205b240065",
              "status": "affected",
              "version": "cc15ff3275694fedc33cd3d53212a43eec7aa0bc",
              "versionType": "git"
            },
            {
              "lessThan": "8079acc5ee5235a627e4586d4f42082a9000ea64",
              "status": "affected",
              "version": "cc15ff3275694fedc33cd3d53212a43eec7aa0bc",
              "versionType": "git"
            },
            {
              "lessThan": "31467b23823ffec1f6fff407f8e3ca9af8b7491a",
              "status": "affected",
              "version": "cc15ff3275694fedc33cd3d53212a43eec7aa0bc",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/powerpc/kernel/time.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.18"
            },
            {
              "lessThan": "5.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.175",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.142",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.92",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.34",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise()\n\nA kernel panic is observed when handling machine check exceptions from\nreal mode.\n\n  BUG: Unable to handle kernel data access on read at 0xc00000006be21300\n  Oops: Kernel access of bad area, sig: 11 [#1]\n  MSR:  8000000000001003 \u003cSF,ME,RI,LE\u003e  CR: 88222248  XER: 00000005\n  CFAR: c00000000003ffc4 DAR: c00000006be21300 DSISR: 40000000 IRQMASK: 0\n  NIP [c000000000029e40] arch_irq_work_raise+0x10/0x70\n  LR [c00000000003ffc8] machine_check_queue_event+0xa8/0x150\n  Call Trace:\n  [c0000000179d3c70] [c00000000003ff64] machine_check_queue_event+0x44/0x150\n  [c0000000179d3d30] [c0000000000084e0] machine_check_early_common+0x1f0/0x2c0\n\nThe crash occurs because arch_irq_work_raise() calls preempt_disable()\nfrom machine check exception (MCE) handlers running in real mode. In\nthis context, accessing the preempt_count can fault, leading to the panic.\n\nThe preempt_disable()/preempt_enable() pair in arch_irq_work_raise()\nwas originally added by commit 0fe1ac48bef0 (\"powerpc/perf_event: Fix\noops due to perf_event_do_pending call\") to avoid races while raising\nirq work from exception context.\n\nLater, commit 471ba0e686cb (\"irq_work: Do not raise an IPI when\nqueueing work on the local CPU\") added preemption protection in\nirq_work_queue() path, while commit 20b876918c06 (\"irq_work: Use per\ncpu atomics instead of regular atomics\") added equivalent\nprotection in irq_work_queue_on() before reaching arch_irq_work_raise():\n\n  irq_work_queue() / irq_work_queue_on()\n    -\u003e preempt_disable()\n      -\u003e __irq_work_queue_local()\n        -\u003e irq_work_raise()\n          -\u003e arch_irq_work_raise()\n\nAs a result, callers other than mce_irq_work_raise() already execute\nwith preemption disabled, making the additional\npreempt_disable()/preempt_enable() pair in arch_irq_work_raise()\nredundant.\n\nThe arch_irq_work_raise() function executes in NMI context when called\nfrom MCE handler. Hence we will not be preempted or scheduled out since\nwe are in NMI context with MSR[EE]=0. Therefore, it is safe to remove\nthe preempt_disable()/preempt_enable() calls from here.\n\nRemove it to avoid accessing preempt_count from real mode context.\n\n[Maddy: Fixed the commit title]"
    }
  ],
  "id": "CVE-2026-64214",
  "lastModified": "2026-07-30T14:59:47.950",
  "metrics": {},
  "published": "2026-07-24T16:16:49.053",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/31467b23823ffec1f6fff407f8e3ca9af8b7491a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/51860e423592893cd7bfa7287d99a3aff4dc3a9d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6dcd072a5ae3aed336e4a67a7d4cc5205b240065"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/72d8d1c36452a4d3ee134b1da48de7518c1329f9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8079acc5ee5235a627e4586d4f42082a9000ea64"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a09d07ac45e283c9861a9ceea06f56d0ba851d22"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}



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