{
  "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-2021-47492",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-47492",
    "idYear": 2021,
    "status": "PUBLISHED",
    "publishedAt": "2024-05-22T08:19:40.759Z",
    "updatedAt": "2026-08-05T08:48:02.710Z",
    "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": "mm, thp: bail out early in collapse_file for writeback page",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm, thp: bail out early in collapse_file for writeback page\n\nCurrently collapse_file does not explicitly check PG_writeback, instead,\npage_has_private and try_to_release_page are used to filter writeback\npages.  This does not work for xfs with blocksize equal to or larger\nthan pagesize, because in such case xfs has no page->private.\n\nThis makes collapse_file bail out early for writeback page.  Otherwise,\nxfs end_page_writeback will panic as follows.\n\n  page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32\n  aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:\"libtest.so\"\n  flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback)\n  raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8\n  raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000\n  page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u))\n  page->mem_cgroup:ffff0000c3e9a000\n  ------------[ cut here ]------------\n  kernel BUG at include/linux/mm.h:1212!\n  Internal error: Oops - BUG: 0 [#1] SMP\n  Modules linked in:\n  BUG: Bad page state in process khugepaged  pfn:84ef32\n   xfs(E)\n  page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32\n   libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ...\n  CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ...\n  pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--)\n  Call trace:\n    end_page_writeback+0x1c0/0x214\n    iomap_finish_page_writeback+0x13c/0x204\n    iomap_finish_ioend+0xe8/0x19c\n    iomap_writepage_end_bio+0x38/0x50\n    bio_endio+0x168/0x1ec\n    blk_update_request+0x278/0x3f0\n    blk_mq_end_request+0x34/0x15c\n    virtblk_request_done+0x38/0x74 [virtio_blk]\n    blk_done_softirq+0xc4/0x110\n    __do_softirq+0x128/0x38c\n    __irq_exit_rcu+0x118/0x150\n    irq_exit+0x1c/0x30\n    __handle_domain_irq+0x8c/0xf0\n    gic_handle_irq+0x84/0x108\n    el1_irq+0xcc/0x180\n    arch_cpu_idle+0x18/0x40\n    default_idle_call+0x4c/0x1a0\n    cpuidle_idle_call+0x168/0x1e0\n    do_idle+0xb4/0x104\n    cpu_startup_entry+0x30/0x9c\n    secondary_start_kernel+0x104/0x180\n  Code: d4210000 b0006161 910c8021 94013f4d (d4210000)\n  ---[ end trace 4a88c6a074082f8c ]---\n  Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0",
              "status": "affected",
              "versionType": "git",
              "lessThan": "69a7fa5cb0de06c8956b040f19a7248c8c8308ca"
            },
            {
              "version": "99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0",
              "status": "affected",
              "versionType": "git",
              "lessThan": "5e669d8ab30ab61dec3c36e27b4711f07611e6fc"
            },
            {
              "version": "99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0",
              "status": "affected",
              "versionType": "git",
              "lessThan": "74c42e1baacf206338b1dd6b6199ac964512b5bb"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "5.4",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "5.4"
            },
            {
              "version": "5.10.77",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "version": "5.14.16",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.14.*"
            },
            {
              "version": "5.15",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}