CVE-2021-47255 kvm: LAPIC: Restore guard to prevent illegal APIC register access

2024-05-2114:19:50

Linux

github.com

kvm

lapic

illegal register access

kernel stack

security vulnerability

linux kernel

6.6 Medium

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

15.6%

JSON

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

kvm: LAPIC: Restore guard to prevent illegal APIC register access

Per the SDM, “any access that touches bytes 4 through 15 of an APIC
register may cause undefined behavior and must not be executed.”
Worse, such an access in kvm_lapic_reg_read can result in a leak of
kernel stack contents. Prior to commit 01402cf81051 (“kvm: LAPIC:
write down valid APIC registers”), such an access was explicitly
disallowed. Restore the guard that was removed in that commit.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/x86/kvm/lapic.c"
    ],
    "versions": [
      {
        "version": "01402cf81051",
        "lessThan": "bf99ea52970c",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "01402cf81051",
        "lessThan": "018685461a5b",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "01402cf81051",
        "lessThan": "a2aff09807fb",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "01402cf81051",
        "lessThan": "218bf772bddd",
        "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/x86/kvm/lapic.c"
    ],
    "versions": [
      {
        "version": "5.3",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.3",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.128",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.46",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.12.13",
        "lessThanOrEqual": "5.12.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.13",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]