{
  "cveId": "CVE-2021-47379",
  "url": "https://patchblox.com/security/cve/CVE-2021-47379",
  "summary": "CVE-2021-47379 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47379, released May 21, 2024. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  blk-cgroup: fix UAF by grabbing blkcg lock befor...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  blk-cgroup: fix UAF by grabbing blkcg lock before destroying blkg pd  KASAN reports a use-after-free report when doing fuzz test:  [693354.104835] ================================================================== [693354.105094] BUG: KASAN: use-after-free in bfq_io_set_weight_legacy\u002B0xd3/0x160 [693354.105336] Read of size 4 at addr ffff888be0a35664 by task sh/1453338  [693354.105607] CPU: 41 PID: 1453338 Comm: sh Kdump: loaded Not tainted 4.18.0-147 [693354.105610] Hardware name: Huawei 2288H V5/BC11SPSCB0, BIOS 0.81 07/02/2018 [693354.105612] Call Trace: [693354.105621]  dump_stack\u002B0xf1/0x19b [693354.105626]  ? show_regs_print_info\u002B0x5/0x5 [693354.105634]  ? printk\u002B0x9c/0xc3 [693354.105638]  ? cpumask_weight\u002B0x1f/0x1f [693354.105648]  print_address_description\u002B0x70/0x360 [693354.105654]  kasan_report\u002B0x1b2/0x330 [693354.105659]  ? bfq_io_set_weight_legacy\u002B0xd3/0x160 [693354.105665]  ? bfq_io_set_weight_legacy\u002B0xd3/0x160 [693354.105670]  bfq_io_set_weight_legacy\u002B0xd3/0x160 [693354.105675]  ? bfq_cpd_init\u002B0x20/0x20 [693354.105683]  cgroup_file_write\u002B0x3aa/0x510 [693354.105693]  ? ___slab_alloc\u002B0x507/0x540 [693354.105698]  ? cgroup_file_poll\u002B0x60/0x60 [693354.105702]  ? 0xffffffff89600000 [693354.105708]  ? usercopy_abort\u002B0x90/0x90 [693354.105716]  ? mutex_lock\u002B0xef/0x180 [693354.105726]  kernfs_fop_write\u002B0x1ab/0x280 [693354.105732]  ? cgroup_file_poll\u002B0x60/0x60 [693354.105738]  vfs_write\u002B0xe7/0x230 [693354.105744]  ksys_write\u002B0xb0/0x140 [693354.105749]  ? __ia32_sys_read\u002B0x50/0x50 [693354.105760]  do_syscall_64\u002B0x112/0x370 [693354.105766]  ? syscall_return_slowpath\u002B0x260/0x260 [693354.105772]  ? do_page_fault\u002B0x9b/0x270 [693354.105779]  ? prepare_exit_to_usermode\u002B0xf9/0x1a0 [693354.105784]  ? enter_from_user_mode\u002B0x30/0x30 [693354.105793]  entry_SYSCALL_64_after_hwframe\u002B0x65/0xca  [693354.105875] Allocated by task 1453337: [693354.106001]  kasan_kmalloc\u002B0xa0/0xd0 [693354.106006]  kmem_cache_alloc_node_trace\u002B0x108/0x220 [693354.106010]  bfq_pd_alloc\u002B0x96/0x120 [693354.106015]  blkcg_activate_policy\u002B0x1b7/0x2b0 [693354.106020]  bfq_create_group_hierarchy\u002B0x1e/0x80 [693354.106026]  bfq_init_queue\u002B0x678/0x8c0 [693354.106031]  blk_mq_init_sched\u002B0x1f8/0x460 [693354.106037]  elevator_switch_mq\u002B0xe1/0x240 [693354.106041]  elevator_switch\u002B0x25/0x40 [693354.106045]  elv_iosched_store\u002B0x1a1/0x230 [693354.106049]  queue_attr_store\u002B0x78/0xb0 [693354.106053]  kernfs_fop_write\u002B0x1ab/0x280 [693354.106056]  vfs_write\u002B0xe7/0x230 [693354.106060]  ksys_write\u002B0xb0/0x140 [693354.106064]  do_syscall_64\u002B0x112/0x370 [693354.106069]  entry_SYSCALL_64_after_hwframe\u002B0x65/0xca  [693354.106114] Freed by task 1453336: [693354.106225]  __kasan_slab_free\u002B0x130/0x180 [693354.106229]  kfree\u002B0x90/0x1b0 [693354.106233]  blkcg_deactivate_policy\u002B0x12c/0x220 [693354.106238]  bfq_exit_queue\u002B0xf5/0x110 [693354.106241]  blk_mq_exit_sched\u002B0x104/0x130 [693354.106245]  __elevator_exit\u002B0x45/0x60 [693354.106249]  elevator_switch_mq\u002B0xd6/0x240 [693354.106253]  elevator_switch\u002B0x25/0x40 [693354.106257]  elv_iosched_store\u002B0x1a1/0x230 [693354.106261]  queue_attr_store\u002B0x78/0xb0 [693354.106264]  kernfs_fop_write\u002B0x1ab/0x280 [693354.106268]  vfs_write\u002B0xe7/0x230 [693354.106271]  ksys_write\u002B0xb0/0x140 [693354.106275]  do_syscall_64\u002B0x112/0x370 [693354.106280]  entry_SYSCALL_64_after_hwframe\u002B0x65/0xca  [693354.106329] The buggy address belongs to the object at ffff888be0a35580                  which belongs to the cache kmalloc-1k of size 1024 [693354.106736] The buggy address is located 228 bytes inside of                  1024-byte region [ffff888be0a35580, ffff888be0a35980) [693354.107114] The buggy address belongs to the page: [693354.107273] page:ffffea002f828c00 count:1 mapcount:0 mapping:ffff888107c17080 index:0x0 compound_mapcount: 0 [693354.107606] flags: 0x17ffffc0008100(slab|head) [693354.107760] raw: 0017ffffc0008100 ffffea002fcbc808 ffffea0030bd3a08 ffff888107c17080 [693354.108020] r ---truncated---",
  "published": "2024-05-21T15:15:23Z",
  "severity": "high",
  "cvss": 7.8,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.00253,
  "epssPercentile": 0.16924,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "5.14.9-1",
      "fix": "DEBIAN-CVE-2021-47379",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47379",
      "released": "2024-05-21T15:15:23Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "5.14.9-1",
      "fix": "DEBIAN-CVE-2021-47379",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47379",
      "released": "2024-05-21T15:15:23Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "5.14.9-1",
      "fix": "DEBIAN-CVE-2021-47379",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47379",
      "released": "2024-05-21T15:15:23Z"
    }
  ],
  "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"
  }
}