CVE-2021-47451 netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/netfilter/xt_IDLETIMER.c"
    ],
    "versions": [
      {
        "version": "68983a354a655c35d3fb204489d383a2a051fda7",
        "lessThan": "2a670c323055282c9b72794a491d53cef86bbeaf",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "68983a354a655c35d3fb204489d383a2a051fda7",
        "lessThan": "cae7cab804c943d723d52724a3aeb07a3f4a2650",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "68983a354a655c35d3fb204489d383a2a051fda7",
        "lessThan": "902c0b1887522a099aa4e1e6b4b476c2fe5dd13e",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/netfilter/xt_IDLETIMER.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"
      }
    ]
  }
]