CVE-2021-47429

2024-05-2115:15:28

416baaa9-dc9f-4396-8d5f-8c081fb06d67

web.nvd.nist.gov

linux kernel

vulnerability fix

powerpc/64s

nmi handler

machine check exception

6.6 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

9.1%

JSON

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

powerpc/64s: Fix unrecoverable MCE calling async handler from NMI

The machine check handler is not considered NMI on 64s. The early
handler is the true NMI handler, and then it schedules the
machine_check_exception handler to run when interrupts are enabled.

This works fine except the case of an unrecoverable MCE, where the true
NMI is taken when MSR[RI] is clear, it can not recover, so it calls
machine_check_exception directly so something might be done about it.

Calling an async handler from NMI context can result in irq state and
other things getting corrupted. This can also trigger the BUG at
arch/powerpc/include/asm/interrupt.h:168
BUG_ON(!arch_irq_disabled_regs(regs) && !(regs->msr & MSR_EE));

Fix this by making an _async version of the handler which is called
in the normal case, and a NMI version that is called for unrecoverable
interrupts.

Affected configurations

Vulners

Node

linuxlinux_kernelRange5.14–5.14.12

linuxlinux_kernelRange5.15.0≥

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/powerpc/include/asm/interrupt.h",
      "arch/powerpc/kernel/exceptions-64s.S",
      "arch/powerpc/kernel/traps.c"
    ],
    "versions": [
      {
        "version": "2b43dd7653cc",
        "lessThan": "d7a8e38999fb",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2b43dd7653cc",
        "lessThan": "f08fb25bc669",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/powerpc/include/asm/interrupt.h",
      "arch/powerpc/kernel/exceptions-64s.S",
      "arch/powerpc/kernel/traps.c"
    ],
    "versions": [
      {
        "version": "5.14",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.14",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.14.12",
        "lessThanOrEqual": "5.14.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]