CVE-2024-44948 x86/mtrr: Check if fixed MTRRs exist before saving them

2024-09-0418:35:48

Linux

www.cve.org

linux kernel

vulnerability resolved

mtrrs

x86 cpus

fine grained caching control

msrs

capability check

EPSS

Percentile

13.7%

JSON

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

x86/mtrr: Check if fixed MTRRs exist before saving them

MTRRs have an obsolete fixed variant for fine grained caching control
of the 640K-1MB region that uses separate MSRs. This fixed variant has
a separate capability bit in the MTRR capability MSR.

So far all x86 CPUs which support MTRR have this separate bit set, so it
went unnoticed that mtrr_save_state() does not check the capability bit
before accessing the fixed MTRR MSRs.

Though on a CPU that does not support the fixed MTRR capability this
results in a #GP. The #GP itself is harmless because the RDMSR fault is
handled gracefully, but results in a WARN_ON().

Add the missing capability check to prevent this.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "arch/x86/kernel/cpu/mtrr/mtrr.c"
    ],
    "versions": [
      {
        "version": "2b1f6278d77c",
        "lessThan": "34f36e6ee5bd",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2b1f6278d77c",
        "lessThan": "06c1de44d378",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2b1f6278d77c",
        "lessThan": "450b6b22acda",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2b1f6278d77c",
        "lessThan": "ca7d00c5656d",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2b1f6278d77c",
        "lessThan": "8aa79dfb216b",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2b1f6278d77c",
        "lessThan": "8a90d3fc7c24",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2b1f6278d77c",
        "lessThan": "388f1c954019",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2b1f6278d77c",
        "lessThan": "919f18f961c0",
        "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/kernel/cpu/mtrr/mtrr.c"
    ],
    "versions": [
      {
        "version": "2.6.22",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "2.6.22",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.320",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.282",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.224",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.165",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.105",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.46",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10.5",
        "lessThanOrEqual": "6.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.11",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]