{
  "cveId": "CVE-2021-46938",
  "url": "https://patchblox.com/security/cve/CVE-2021-46938",
  "summary": "CVE-2021-46938 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-46938, released February 27, 2024. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  dm rq: fix double free of blk_mq_tag_set in dev...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  dm rq: fix double free of blk_mq_tag_set in dev remove after table load fails  When loading a device-mapper table for a request-based mapped device, and the allocation/initialization of the blk_mq_tag_set for the device fails, a following device remove will cause a double free.  E.g. (dmesg):   device-mapper: core: Cannot initialize queue for request-based dm-mq mapped device   device-mapper: ioctl: unable to set up device queue for new table.   Unable to handle kernel pointer dereference in virtual kernel address space   Failing address: 0305e098835de000 TEID: 0305e098835de803   Fault in home space mode while using kernel ASCE.   AS:000000025efe0007 R3:0000000000000024   Oops: 0038 ilc:3 [#1] SMP   Modules linked in: ... lots of modules ...   Supported: Yes, External   CPU: 0 PID: 7348 Comm: multipathd Kdump: loaded Tainted: G        W      X    5.3.18-53-default #1 SLE15-SP3   Hardware name: IBM 8561 T01 7I2 (LPAR)   Krnl PSW : 0704e00180000000 000000025e368eca (kfree\u002B0x42/0x330)              R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3   Krnl GPRS: 000000000000004a 000000025efe5230 c1773200d779968d 0000000000000000              000000025e520270 000000025e8d1b40 0000000000000003 00000007aae10000              000000025e5202a2 0000000000000001 c1773200d779968d 0305e098835de640              00000007a8170000 000003ff80138650 000000025e5202a2 000003e00396faa8   Krnl Code: 000000025e368eb8: c4180041e100       lgrl    %r1,25eba50b8              000000025e368ebe: ecba06b93a55       risbg   %r11,%r10,6,185,58             #000000025e368ec4: e3b010000008       ag      %r11,0(%r1)             \u003E000000025e368eca: e310b0080004       lg      %r1,8(%r11)              000000025e368ed0: a7110001           tmll    %r1,1              000000025e368ed4: a7740129           brc     7,25e369126              000000025e368ed8: e320b0080004       lg      %r2,8(%r11)              000000025e368ede: b904001b           lgr     %r1,%r11   Call Trace:    [\u003C000000025e368eca\u003E] kfree\u002B0x42/0x330    [\u003C000000025e5202a2\u003E] blk_mq_free_tag_set\u002B0x72/0xb8    [\u003C000003ff801316a8\u003E] dm_mq_cleanup_mapped_device\u002B0x38/0x50 [dm_mod]    [\u003C000003ff80120082\u003E] free_dev\u002B0x52/0xd0 [dm_mod]    [\u003C000003ff801233f0\u003E] __dm_destroy\u002B0x150/0x1d0 [dm_mod]    [\u003C000003ff8012bb9a\u003E] dev_remove\u002B0x162/0x1c0 [dm_mod]    [\u003C000003ff8012a988\u003E] ctl_ioctl\u002B0x198/0x478 [dm_mod]    [\u003C000003ff8012ac8a\u003E] dm_ctl_ioctl\u002B0x22/0x38 [dm_mod]    [\u003C000000025e3b11ee\u003E] ksys_ioctl\u002B0xbe/0xe0    [\u003C000000025e3b127a\u003E] __s390x_sys_ioctl\u002B0x2a/0x40    [\u003C000000025e8c15ac\u003E] system_call\u002B0xd8/0x2c8   Last Breaking-Event-Address:    [\u003C000000025e52029c\u003E] blk_mq_free_tag_set\u002B0x6c/0xb8   Kernel panic - not syncing: Fatal exception: panic_on_oops  When allocation/initialization of the blk_mq_tag_set fails in dm_mq_init_request_queue(), it is uninitialized/freed, but the pointer is not reset to NULL; so when dev_remove() later gets into dm_mq_cleanup_mapped_device() it sees the pointer and tries to uninitialize and free it again.  Fix this by setting the pointer to NULL in dm_mq_init_request_queue() error-handling. Also set it to NULL in dm_mq_cleanup_mapped_device().",
  "published": "2024-02-27T19:04:05Z",
  "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": 0.00248,
  "epssPercentile": 0.16175,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "5.10.38-1",
      "fix": "DEBIAN-CVE-2021-46938",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-46938",
      "released": "2024-02-27T19:04:05Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "5.10.38-1",
      "fix": "DEBIAN-CVE-2021-46938",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-46938",
      "released": "2024-02-27T19:04:05Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "5.10.38-1",
      "fix": "DEBIAN-CVE-2021-46938",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-46938",
      "released": "2024-02-27T19:04:05Z"
    }
  ],
  "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"
  }
}