FKIE_CVE-2026-98809

Vulnerability from fkie_nvd - Published: 2026-10-18 16:17 - Updated: 2026-10-30 13:21
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister hci_unregister_dev() disables cmd_work and cmd_timer, then calls hci_cmd_sync_clear(), whose cancel_work_sync() waits for hci_cmd_sync_work() to return. That worker dequeues and runs every entry on cmd_sync_work_list. With cmd_work disabled nothing reaches the controller, so each queued HCI command waits the full HCI_CMD_TIMEOUT (2s). The backlog has no bound. Userspace can keep queuing MGMT commands such as MGMT_OP_GET_CLOCK_INFO against a controller that doesn't answer. Closing /dev/vhci then blocks in vhci_release() for backlog * 2s: INFO: task syz-executor:5749 blocked for more than 143 seconds. cancel_work_sync hci_cmd_sync_clear hci_unregister_dev vhci_release In a local reproduction the backlog held more than 5000 entries, which comes to hours of hang. Stop the worker from taking new entries once HCI_UNREGISTER is set, and wake any request still waiting with -ENODEV before cancelling the work. The entries left over are destroyed with -ECANCELED by the existing sweep in hci_cmd_sync_clear(). They stay on the list until the work has stopped, so hci_cmd_sync_dequeue() and friends still see them. A callback already running may still issue another command, which delays unregister by at most one timeout per remaining command, not by the whole backlog.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/143bde97c4101ae68eb656c87e620c45b07a3090
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7f16443a30f4e86d84ae4faf057d333b41ddb757
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b06d85b114cc5fa61809f9950bca66502e0e1173
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b11acfcb5925ed27fae692b27931a1ac732677fb
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b1f24c1ab52345e810c42a1a81286cb5a7c92252
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/hci_sync.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b06d85b114cc5fa61809f9950bca66502e0e1173",
              "status": "affected",
              "version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
              "versionType": "git"
            },
            {
              "lessThan": "b11acfcb5925ed27fae692b27931a1ac732677fb",
              "status": "affected",
              "version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
              "versionType": "git"
            },
            {
              "lessThan": "143bde97c4101ae68eb656c87e620c45b07a3090",
              "status": "affected",
              "version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
              "versionType": "git"
            },
            {
              "lessThan": "7f16443a30f4e86d84ae4faf057d333b41ddb757",
              "status": "affected",
              "version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
              "versionType": "git"
            },
            {
              "lessThan": "e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c",
              "status": "affected",
              "version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
              "versionType": "git"
            },
            {
              "lessThan": "b1f24c1ab52345e810c42a1a81286cb5a7c92252",
              "status": "affected",
              "version": "008ee9eb8a11bcabf12c91771dd4f470b082bd44",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/hci_sync.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.17"
            },
            {
              "lessThan": "5.17",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.191",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.113",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.56",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_sync: don\u0027t drain cmd_sync backlog on unregister\n\nhci_unregister_dev() disables cmd_work and cmd_timer, then calls\nhci_cmd_sync_clear(), whose cancel_work_sync() waits for\nhci_cmd_sync_work() to return. That worker dequeues and runs every\nentry on cmd_sync_work_list. With cmd_work disabled nothing reaches\nthe controller, so each queued HCI command waits the full\nHCI_CMD_TIMEOUT (2s).\n\nThe backlog has no bound. Userspace can keep queuing MGMT commands\nsuch as MGMT_OP_GET_CLOCK_INFO against a controller that doesn\u0027t\nanswer. Closing /dev/vhci then blocks in vhci_release() for\nbacklog * 2s:\n\n  INFO: task syz-executor:5749 blocked for more than 143 seconds.\n   cancel_work_sync\n   hci_cmd_sync_clear\n   hci_unregister_dev\n   vhci_release\n\nIn a local reproduction the backlog held more than 5000 entries,\nwhich comes to hours of hang.\n\nStop the worker from taking new entries once HCI_UNREGISTER is set,\nand wake any request still waiting with -ENODEV before cancelling\nthe work. The entries left over are destroyed with -ECANCELED by the\nexisting sweep in hci_cmd_sync_clear(). They stay on the list until\nthe work has stopped, so hci_cmd_sync_dequeue() and friends still see\nthem. A callback already running may still issue another command,\nwhich delays unregister by at most one timeout per remaining command,\nnot by the whole backlog."
    }
  ],
  "id": "CVE-2026-98809",
  "lastModified": "2026-10-30T13:21:28.643",
  "metrics": {},
  "published": "2026-10-18T16:17:34.997",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/143bde97c4101ae68eb656c87e620c45b07a3090"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7f16443a30f4e86d84ae4faf057d333b41ddb757"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b06d85b114cc5fa61809f9950bca66502e0e1173"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b11acfcb5925ed27fae692b27931a1ac732677fb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b1f24c1ab52345e810c42a1a81286cb5a7c92252"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e8ba8c9c74d1035042cdf6cb5adf8f59b9b1271c"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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