Description (CNA)
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.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected de5a44f351ca7efd9add9851b218f5353e2224b7 before 55b76500546e5f2e7fdd7ae7283530b620de6e61; affected 7b277bd569bb6a2777f0014f84b4344f444fd49d before 66cc55b69928b742d24b4c5b66d195ae96900e48; affected 27aabf27fd014ae037cc179c61b0bee7cff55b3d before eeabdb25c3209569367e99a85ca9a503b64a646d; affected 27aabf27fd014ae037cc179c61b0bee7cff55b3d before 9e9ece97b8e716890793de261574b8efef7d8702; affected 27aabf27fd014ae037cc179c61b0bee7cff55b3d before 9b851b09b392da68bd715601f10a5adb2d8d19b8; affected 6894717a1ea363c5a27010ba604f957c309d282d; affected fb91ce37dc9a37ea23cf32b6d7b667004e93d4c5; affected a9584c897d1cba6265c78010bbb45ca5722c88bc; affected 0f67ca2a80acf8b207240405b7f72d660665d3df; affected 91e2a2e4d1336333804cd31162984f01ad8cc70f; affected 6.6.64 before 6.6.160; affected 6.12.2 before 6.12.114; affected 5.4.297 before 5.5; affected 5.10.231 before 5.11; affected 5.15.174 before 5.16; affected 6.1.120 before 6.2; affected 6.11.11 before 6.12 |
| Linux / Linux | affected 6.13; unaffected 0 before 6.13; unaffected 6.6.160 through 6.6.*; unaffected 6.12.114 through 6.12.*; unaffected 6.18.53 through 6.18.*; unaffected 7.2.7 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/55b76500546e5f2e7fdd7ae7283530b620de6e61
- https://git.kernel.org/stable/c/66cc55b69928b742d24b4c5b66d195ae96900e48
- https://git.kernel.org/stable/c/eeabdb25c3209569367e99a85ca9a503b64a646d
- https://git.kernel.org/stable/c/9e9ece97b8e716890793de261574b8efef7d8702
- https://git.kernel.org/stable/c/9b851b09b392da68bd715601f10a5adb2d8d19b8