{
  "cveId": "CVE-2021-47488",
  "url": "https://patchblox.com/security/cve/CVE-2021-47488",
  "summary": "CVE-2021-47488 is fixed in linux on 1 platform, first by CVE-2021-47488, 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:\n\ncgroup: Fix memory leak caused by missing cgroup...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup: Fix memory leak caused by missing cgroup_bpf_offline\n\nWhen enabling CONFIG_CGROUP_BPF, kmemleak can be observed by running\nthe command as below:\n\n    $mount -t cgroup -o none,name=foo cgroup cgroup/\n    $umount cgroup/\n\nunreferenced object 0xc3585c40 (size 64):\n  comm \u0022mount\u0022, pid 425, jiffies 4294959825 (age 31.990s)\n  hex dump (first 32 bytes):\n    01 00 00 80 84 8c 28 c0 00 00 00 00 00 00 00 00  ......(.........\n    00 00 00 00 00 00 00 00 6c 43 a0 c3 00 00 00 00  ........lC......\n  backtrace:\n    [\u003Ce95a2f9e\u003E] cgroup_bpf_inherit\u002B0x44/0x24c\n    [\u003C1f03679c\u003E] cgroup_setup_root\u002B0x174/0x37c\n    [\u003Ced4b0ac5\u003E] cgroup1_get_tree\u002B0x2c0/0x4a0\n    [\u003Cf85b12fd\u003E] vfs_get_tree\u002B0x24/0x108\n    [\u003Cf55aec5c\u003E] path_mount\u002B0x384/0x988\n    [\u003Ce2d5e9cd\u003E] do_mount\u002B0x64/0x9c\n    [\u003C208c9cfe\u003E] sys_mount\u002B0xfc/0x1f4\n    [\u003C06dd06e0\u003E] ret_fast_syscall\u002B0x0/0x48\n    [\u003Ca8308cb3\u003E] 0xbeb4daa8\n\nThis is because that since the commit 2b0d3d3e4fcf (\u0022percpu_ref: reduce\nmemory footprint of percpu_ref in fast path\u0022) root_cgrp-\u003Ebpf.refcnt.data\nis allocated by the function percpu_ref_init in cgroup_bpf_inherit which\nis called by cgroup_setup_root when mounting, but not freed along with\nroot_cgrp when umounting. Adding cgroup_bpf_offline which calls\npercpu_ref_kill to cgroup_kill_sb can free root_cgrp-\u003Ebpf.refcnt.data in\numount path.\n\nThis patch also fixes the commit 4bfc0bb2c60e (\u0022bpf: decouple the lifetime\nof cgroup_bpf from cgroup itself\u0022). A cgroup_bpf_offline is needed to do a\ncleanup that frees the resources which are allocated by cgroup_bpf_inherit\nin cgroup_setup_root.\n\nAnd inside cgroup_bpf_offline, cgroup_get() is at the beginning and\ncgroup_put is at the end of cgroup_bpf_release which is called by\ncgroup_bpf_offline. So cgroup_bpf_offline can keep the balance of\ncgroup\u0027s refcount.",
  "published": "2024-05-22T09:15:10Z",
  "severity": "",
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 11.6 (bullseye)",
      "fixedVersion": "5.10.84-1",
      "fix": "CVE-2021-47488",
      "url": "https://patchblox.com/security/fix/linux/cve-2021-47488",
      "released": "2024-05-22T09:15:10Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "5.15.3-1",
      "fix": "CVE-2021-47488",
      "url": "https://patchblox.com/security/fix/linux/cve-2021-47488",
      "released": "2024-05-22T09:15:10Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "5.15.3-1",
      "fix": "CVE-2021-47488",
      "url": "https://patchblox.com/security/fix/linux/cve-2021-47488",
      "released": "2024-05-22T09:15:10Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T06:59:42Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}