CVE-2021-47461 userfaultfd: fix a race between writeprotect and exit_mmap()

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/userfaultfd.c"
    ],
    "versions": [
      {
        "version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
        "lessThan": "3cda4bfffd4f755645577aaa9e96a606657b4525",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
        "lessThan": "149958ecd0627a9f1e9c678c25c665400054cd6a",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "63b2d4174c4ad1f40b48d7138e71bcb564c1fe03",
        "lessThan": "cb185d5f1ebf900f4ae3bf84cee212e6dd035aca",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/userfaultfd.c"
    ],
    "versions": [
      {
        "version": "5.7",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.7",
        "status": "unaffected",
        "versionType": "semver"
      },
      {
        "version": "5.10.76",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "semver"
      },
      {
        "version": "5.14.15",
        "lessThanOrEqual": "5.14.*",
        "status": "unaffected",
        "versionType": "semver"
      },
      {
        "version": "5.15",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]