FKIE_CVE-2026-97975

Vulnerability from fkie_nvd - Published: 2026-09-25 11:17 - Updated: 2026-09-25 11:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_sysfs: Fix NULL pointer dereference in device_del() A NULL pointer dereference in klist_put() occurs when a child device (such as a BNEP network device in bnep_session) is concurrently being unregistered while hci_conn_del_sysfs() reparents child devices. This is caused by a race condition between hci_conn_del_sysfs() and concurrent child device unregistration (e.g. bnep_session calling unregister_netdev()). During device unregistration, device_del() snapshots a non-NULL parent pointer. Concurrently, hci_conn_del_sysfs() finds the child device using device_find_any_child() and calls device_move() to reparent it to NULL, which removes the node from its parent's klist and clears knode_parent. Subsequently, device_del() calls klist_del(&dev->p->knode_parent) using the stale parent snapshot, causing klist_put() to dereference knode_klist(n)->put on an already removed node, resulting in a NULL pointer dereference. This race was introduced by commit 27aabf27fd01 ("Bluetooth: fix use-after-free in device_for_each_child()"), which replaced device_find_child(..., __match_tty) with device_find_any_child() in hci_conn_del_sysfs(). That change was intended to avoid a use-after-free where conn->dev outlived its parent hdev->dev when child devices held references to conn->dev, because conn->dev only held a reference to hdev->dev while registered in sysfs. Fix the issue properly by taking an explicit reference to the parent device with get_device(&hdev->dev) in hci_conn_init_sysfs() and dropping it with put_device(parent) in bt_link_release() when the conn device is freed. This ensures that hdev->dev remains valid for the entire lifecycle of conn->dev, resolving the underlying use-after-free. With the parent reference held properly, restore the __match_tty filter in hci_conn_del_sysfs() so that device_move() is only invoked on persistent RFCOMM TTY devices as originally intended, eliminating the race condition with unregistering network devices.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9b851b09b392da68bd715601f10a5adb2d8d19b8
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9e9ece97b8e716890793de261574b8efef7d8702
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/eeabdb25c3209569367e99a85ca9a503b64a646d
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/hci_sysfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "eeabdb25c3209569367e99a85ca9a503b64a646d",
              "status": "affected",
              "version": "27aabf27fd014ae037cc179c61b0bee7cff55b3d",
              "versionType": "git"
            },
            {
              "lessThan": "9e9ece97b8e716890793de261574b8efef7d8702",
              "status": "affected",
              "version": "27aabf27fd014ae037cc179c61b0bee7cff55b3d",
              "versionType": "git"
            },
            {
              "lessThan": "9b851b09b392da68bd715601f10a5adb2d8d19b8",
              "status": "affected",
              "version": "27aabf27fd014ae037cc179c61b0bee7cff55b3d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "6894717a1ea363c5a27010ba604f957c309d282d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "fb91ce37dc9a37ea23cf32b6d7b667004e93d4c5",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "a9584c897d1cba6265c78010bbb45ca5722c88bc",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0f67ca2a80acf8b207240405b7f72d660665d3df",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "de5a44f351ca7efd9add9851b218f5353e2224b7",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "91e2a2e4d1336333804cd31162984f01ad8cc70f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "7b277bd569bb6a2777f0014f84b4344f444fd49d",
              "versionType": "git"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.297",
              "versionType": "semver"
            },
            {
              "lessThan": "5.11",
              "status": "affected",
              "version": "5.10.231",
              "versionType": "semver"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.174",
              "versionType": "semver"
            },
            {
              "lessThan": "6.2",
              "status": "affected",
              "version": "6.1.120",
              "versionType": "semver"
            },
            {
              "lessThan": "6.7",
              "status": "affected",
              "version": "6.6.64",
              "versionType": "semver"
            },
            {
              "lessThan": "6.12",
              "status": "affected",
              "version": "6.11.11",
              "versionType": "semver"
            },
            {
              "lessThan": "6.13",
              "status": "affected",
              "version": "6.12.2",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/bluetooth/hci_sysfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.13"
            },
            {
              "lessThan": "6.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc3",
              "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_sysfs: Fix NULL pointer dereference in device_del()\n\nA NULL pointer dereference in klist_put() occurs when a child device (such\nas a BNEP network device in bnep_session) is concurrently being\nunregistered while hci_conn_del_sysfs() reparents child devices.\n\nThis is caused by a race condition between hci_conn_del_sysfs() and\nconcurrent child device unregistration (e.g. bnep_session calling\nunregister_netdev()). During device unregistration, device_del() snapshots\na non-NULL parent pointer. Concurrently, hci_conn_del_sysfs() finds the\nchild device using device_find_any_child() and calls device_move() to\nreparent it to NULL, which removes the node from its parent\u0027s klist and\nclears knode_parent. Subsequently, device_del() calls\nklist_del(\u0026dev-\u003ep-\u003eknode_parent) using the stale parent snapshot, causing\nklist_put() to dereference knode_klist(n)-\u003eput on an already removed node,\nresulting in a NULL pointer dereference.\n\nThis race was introduced by commit 27aabf27fd01 (\"Bluetooth: fix\nuse-after-free in device_for_each_child()\"), which replaced\ndevice_find_child(..., __match_tty) with device_find_any_child() in\nhci_conn_del_sysfs(). That change was intended to avoid a use-after-free\nwhere conn-\u003edev outlived its parent hdev-\u003edev when child devices held\nreferences to conn-\u003edev, because conn-\u003edev only held a reference to\nhdev-\u003edev while registered in sysfs.\n\nFix the issue properly by taking an explicit reference to the parent device\nwith get_device(\u0026hdev-\u003edev) in hci_conn_init_sysfs() and dropping it with\nput_device(parent) in bt_link_release() when the conn device is freed. This\nensures that hdev-\u003edev remains valid for the entire lifecycle of conn-\u003edev,\nresolving the underlying use-after-free. With the parent reference held\nproperly, restore the __match_tty filter in hci_conn_del_sysfs() so that\ndevice_move() is only invoked on persistent RFCOMM TTY devices as\noriginally intended, eliminating the race condition with unregistering\nnetwork devices."
    }
  ],
  "id": "CVE-2026-97975",
  "lastModified": "2026-09-25T11:17:25.427",
  "metrics": {},
  "published": "2026-09-25T11:17:25.427",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9b851b09b392da68bd715601f10a5adb2d8d19b8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9e9ece97b8e716890793de261574b8efef7d8702"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/eeabdb25c3209569367e99a85ca9a503b64a646d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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