{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2021-47584",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-47584",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2024-06-19T14:53:50.119Z",
    "updatedAt": "2026-05-11T13:57:22.259Z",
    "importedAt": "2026-10-24T01:56:36.661Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "iocost: Fix divide-by-zero on donation from low hweight cgroup",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\niocost: Fix divide-by-zero on donation from low hweight cgroup\n\nThe donation calculation logic assumes that the donor has non-zero\nafter-donation hweight, so the lowest active hweight a donating cgroup can\nhave is 2 so that it can donate 1 while keeping the other 1 for itself.\nEarlier, we only donated from cgroups with sizable surpluses so this\ncondition was always true. However, with the precise donation algorithm\nimplemented, f1de2439ec43 (\"blk-iocost: revamp donation amount\ndetermination\") made the donation amount calculation exact enabling even low\nhweight cgroups to donate.\n\nThis means that in rare occasions, a cgroup with active hweight of 1 can\nenter donation calculation triggering the following warning and then a\ndivide-by-zero oops.\n\n WARNING: CPU: 4 PID: 0 at block/blk-iocost.c:1928 transfer_surpluses.cold+0x0/0x53 [884/94867]\n ...\n RIP: 0010:transfer_surpluses.cold+0x0/0x53\n Code: 92 ff 48 c7 c7 28 d1 ab b5 65 48 8b 34 25 00 ae 01 00 48 81 c6 90 06 00 00 e8 8b 3f fe ff 48 c7 c0 ea ff ff ff e9 95 ff 92 ff <0f> 0b 48 c7 c7 30 da ab b5 e8 71 3f fe ff 4c 89 e8 4d 85 ed 74 0\n4\n ...\n Call Trace:\n  <IRQ>\n  ioc_timer_fn+0x1043/0x1390\n  call_timer_fn+0xa1/0x2c0\n  __run_timers.part.0+0x1ec/0x2e0\n  run_timer_softirq+0x35/0x70\n ...\n iocg: invalid donation weights in /a/b: active=1 donating=1 after=0\n\nFix it by excluding cgroups w/ active hweight < 2 from donating. Excluding\nthese extreme low hweight donations shouldn't affect work conservation in\nany meaningful way.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "f1de2439ec43b74764f2a26e3a310b24407e3bde",
              "status": "affected",
              "versionType": "git",
              "lessThan": "a7c80674538f15f85d68138240aae440b8039519"
            },
            {
              "version": "f1de2439ec43b74764f2a26e3a310b24407e3bde",
              "status": "affected",
              "versionType": "git",
              "lessThan": "3a1a4eb574178c21241a6200f4785572e661c472"
            },
            {
              "version": "f1de2439ec43b74764f2a26e3a310b24407e3bde",
              "status": "affected",
              "versionType": "git",
              "lessThan": "edaa26334c117a584add6053f48d63a988d25a6e"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "5.10",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "5.10"
            },
            {
              "version": "5.10.88",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "version": "5.15.11",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "version": "5.16",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}