{
   affected: [],
   aliases: [
      "CVE-2021-47488",
   ],
   database_specific: {
      cwe_ids: [],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-05-22T09:15:10Z",
      severity: null,
   },
   details: "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 \"mount\", 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    [<e95a2f9e>] cgroup_bpf_inherit+0x44/0x24c\n    [<1f03679c>] cgroup_setup_root+0x174/0x37c\n    [<ed4b0ac5>] cgroup1_get_tree+0x2c0/0x4a0\n    [<f85b12fd>] vfs_get_tree+0x24/0x108\n    [<f55aec5c>] path_mount+0x384/0x988\n    [<e2d5e9cd>] do_mount+0x64/0x9c\n    [<208c9cfe>] sys_mount+0xfc/0x1f4\n    [<06dd06e0>] ret_fast_syscall+0x0/0x48\n    [<a8308cb3>] 0xbeb4daa8\n\nThis is because that since the commit 2b0d3d3e4fcf (\"percpu_ref: reduce\nmemory footprint of percpu_ref in fast path\") root_cgrp->bpf.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->bpf.refcnt.data in\numount path.\n\nThis patch also fixes the commit 4bfc0bb2c60e (\"bpf: decouple the lifetime\nof cgroup_bpf from cgroup itself\"). 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's refcount.",
   id: "GHSA-xvmj-27r5-9623",
   modified: "2024-05-22T09:31:46Z",
   published: "2024-05-22T09:31:46Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2021-47488",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/01599bf7cc2b49c3d2be886cb438647dc25446ed",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/04f8ef5643bcd8bcde25dfdebef998aea480b2ba",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/b529f88d93884cf8ccafda793ee3d27b82fa578d",
      },
   ],
   schema_version: "1.4.0",
   severity: [],
}