CVE-2021-47491

2024-05-2209:15:10

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

web.nvd.nist.gov

linux kernel

mm khugepaged

thp

filesystems

files

tlb

bugs

6.6 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.6%

JSON

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

mm: khugepaged: skip huge page collapse for special files

The read-only THP for filesystems will collapse THP for files opened
readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB
misses for large text segments. But it doesn’t restrict the file types
so a THP could be collapsed for a non-regular file, for example, block
device, if it is opened readonly and mapped with EXEC permission. This
may cause bugs, like [1] and [2].

This is definitely not the intended usecase, so just collapse THP for
regular files in order to close the attack surface.

[[email protected]: fix vm_file check [3]]

Affected configurations

Vulners

Node

linuxlinux_kernelRange5.4–5.10.78

linuxlinux_kernelRange5.11.0–5.14.16

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": [
      "mm/khugepaged.c"
    ],
    "versions": [
      {
        "version": "99cb0dbd47a1",
        "lessThan": "6d67b2a73b8e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "99cb0dbd47a1",
        "lessThan": "5fcb6fce74ff",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "99cb0dbd47a1",
        "lessThan": "a4aeaa06d45e",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "mm/khugepaged.c"
    ],
    "versions": [
      {
        "version": "5.4",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.4",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.78",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.14.16",
        "lessThanOrEqual": "5.14.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]