{
  "cveId": "CVE-2021-47375",
  "url": "https://patchblox.com/security/cve/CVE-2021-47375",
  "summary": "CVE-2021-47375 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47375, released May 21, 2024. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  blktrace: Fix uaf in blk_trace access after remo...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  blktrace: Fix uaf in blk_trace access after removing by sysfs  There is an use-after-free problem triggered by following process:        P1(sda)\t\t\t\tP2(sdb) \t\t\techo 0 \u003E /sys/block/sdb/trace/enable \t\t\t  blk_trace_remove_queue \t\t\t    synchronize_rcu \t\t\t    blk_trace_free \t\t\t      relay_close rcu_read_lock __blk_add_trace   trace_note_tsk   (Iterate running_trace_list) \t\t\t        relay_close_buf \t\t\t\t  relay_destroy_buf \t\t\t\t    kfree(buf)     trace_note(sdb\u0027s bt)       relay_reserve         buf-\u003Eoffset \u003C- nullptr deference (use-after-free) !!! rcu_read_unlock  [  502.714379] BUG: kernel NULL pointer dereference, address: 0000000000000010 [  502.715260] #PF: supervisor read access in kernel mode [  502.715903] #PF: error_code(0x0000) - not-present page [  502.716546] PGD 103984067 P4D 103984067 PUD 17592b067 PMD 0 [  502.717252] Oops: 0000 [#1] SMP [  502.720308] RIP: 0010:trace_note.isra.0\u002B0x86/0x360 [  502.732872] Call Trace: [  502.733193]  __blk_add_trace.cold\u002B0x137/0x1a3 [  502.733734]  blk_add_trace_rq\u002B0x7b/0xd0 [  502.734207]  blk_add_trace_rq_issue\u002B0x54/0xa0 [  502.734755]  blk_mq_start_request\u002B0xde/0x1b0 [  502.735287]  scsi_queue_rq\u002B0x528/0x1140 ... [  502.742704]  sg_new_write.isra.0\u002B0x16e/0x3e0 [  502.747501]  sg_ioctl\u002B0x466/0x1100  Reproduce method:   ioctl(/dev/sda, BLKTRACESETUP, blk_user_trace_setup[buf_size=127])   ioctl(/dev/sda, BLKTRACESTART)   ioctl(/dev/sdb, BLKTRACESETUP, blk_user_trace_setup[buf_size=127])   ioctl(/dev/sdb, BLKTRACESTART)    echo 0 \u003E /sys/block/sdb/trace/enable \u0026   // Add delay(mdelay/msleep) before kernel enters blk_trace_free()    ioctl$SG_IO(/dev/sda, SG_IO, ...)   // Enters trace_note_tsk() after blk_trace_free() returned   // Use mdelay in rcu region rather than msleep(which may schedule out)  Remove blk_trace from running_list before calling blk_trace_free() by sysfs if blk_trace is at Blktrace_running state.",
  "published": "2024-05-21T15:15:23Z",
  "severity": "medium",
  "cvss": 6.2,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
  "epss": 0.00254,
  "epssPercentile": 0.16969,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "5.14.9-1",
      "fix": "DEBIAN-CVE-2021-47375",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47375",
      "released": "2024-05-21T15:15:23Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "5.14.9-1",
      "fix": "DEBIAN-CVE-2021-47375",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47375",
      "released": "2024-05-21T15:15:23Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "5.14.9-1",
      "fix": "DEBIAN-CVE-2021-47375",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47375",
      "released": "2024-05-21T15:15:23Z"
    }
  ],
  "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"
  }
}