{
  "cveId": "CVE-2021-47492",
  "url": "https://patchblox.com/security/cve/CVE-2021-47492",
  "summary": "CVE-2021-47492 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47492, released May 22, 2024. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  mm, thp: bail out early in collapse_file for wri...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  mm, thp: bail out early in collapse_file for writeback page  Currently collapse_file does not explicitly check PG_writeback, instead, page_has_private and try_to_release_page are used to filter writeback pages.  This does not work for xfs with blocksize equal to or larger than pagesize, because in such case xfs has no page-\u003Eprivate.  This makes collapse_file bail out early for writeback page.  Otherwise, xfs end_page_writeback will panic as follows.    page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32   aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:\u0022libtest.so\u0022   flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback)   raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8   raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000   page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) \u002B 127u \u003C= 127u))   page-\u003Emem_cgroup:ffff0000c3e9a000   ------------[ cut here ]------------   kernel BUG at include/linux/mm.h:1212!   Internal error: Oops - BUG: 0 [#1] SMP   Modules linked in:   BUG: Bad page state in process khugepaged  pfn:84ef32    xfs(E)   page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32    libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ...   CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ...   pstate: 60400005 (nZCv daif \u002BPAN -UAO -TCO BTYPE=--)   Call trace:     end_page_writeback\u002B0x1c0/0x214     iomap_finish_page_writeback\u002B0x13c/0x204     iomap_finish_ioend\u002B0xe8/0x19c     iomap_writepage_end_bio\u002B0x38/0x50     bio_endio\u002B0x168/0x1ec     blk_update_request\u002B0x278/0x3f0     blk_mq_end_request\u002B0x34/0x15c     virtblk_request_done\u002B0x38/0x74 [virtio_blk]     blk_done_softirq\u002B0xc4/0x110     __do_softirq\u002B0x128/0x38c     __irq_exit_rcu\u002B0x118/0x150     irq_exit\u002B0x1c/0x30     __handle_domain_irq\u002B0x8c/0xf0     gic_handle_irq\u002B0x84/0x108     el1_irq\u002B0xcc/0x180     arch_cpu_idle\u002B0x18/0x40     default_idle_call\u002B0x4c/0x1a0     cpuidle_idle_call\u002B0x168/0x1e0     do_idle\u002B0xb4/0x104     cpu_startup_entry\u002B0x30/0x9c     secondary_start_kernel\u002B0x104/0x180   Code: d4210000 b0006161 910c8021 94013f4d (d4210000)   ---[ end trace 4a88c6a074082f8c ]---   Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt",
  "published": "2024-05-22T09:15:11Z",
  "severity": "medium",
  "cvss": 5.5,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
  "epss": 0.00218,
  "epssPercentile": 0.12353,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "5.15.3-1",
      "fix": "DEBIAN-CVE-2021-47492",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47492",
      "released": "2024-05-22T09:15:11Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "5.15.3-1",
      "fix": "DEBIAN-CVE-2021-47492",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47492",
      "released": "2024-05-22T09:15:11Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "5.15.3-1",
      "fix": "DEBIAN-CVE-2021-47492",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47492",
      "released": "2024-05-22T09:15:11Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T07:25:28Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}