Bluetooth: hci_sock: Serialize dead-device detachment

Overview

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: hci_sock: Serialize dead-device detachment

Rebinding an HCI socket after its controller is unregistered can race monitor control replay and crash the kernel. hci_sock_bind() clears hci_pi(sk)->hdev and drops the device reference under only the socket lock, whereas send_monitor_control_replay() holds hci_sk_list.lock for reading.

Replay can observe a non-NULL hdev, then bind can clear it and drop the last reference before create_monitor_ctrl_open() reads hdev->id. This can cause a NULL pointer dereference if the pointer is reloaded, or a use-after-free if the old pointer is retained.

The kernel reported:

KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f] RIP: 0010:create_monitor_ctrl_open+0x579/0x800 Call Trace: hci_sock_bind+0xd96/0x1190 __sys_bind+0x166/0x200 __x64_sys_bind+0x6d/0xb0 do_syscall_64+0xdd/0x4a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The same missing serialization lets hci_send_to_sock() select a socket for the old device and queue its frame after bind has detached the socket or installed a new binding.

Take hci_sk_list.lock for writing when clearing the device pointer and resetting the socket state. This waits for existing replay and delivery readers to finish before detachment and prevents later readers from using the old binding. Keep hci_dev_put() outside the critical section because the final device release can sleep.

Affected

• Linux >= e04480920d1eec9c061841399aa6f35b6f987d8b < 37cef0c8fb537f40600910d2c2e5f2d5509305f3
• Linux >= e04480920d1eec9c061841399aa6f35b6f987d8b < 76f2e2665697340ac719e7ff1bf148dd014e55c1
• Linux >= e04480920d1eec9c061841399aa6f35b6f987d8b < c3d2799877906d0c8392d96e14216cd82b020330
• Linux >= e04480920d1eec9c061841399aa6f35b6f987d8b < e660a22402944f2615a16fde7129a3c497537329
• Linux >= e04480920d1eec9c061841399aa6f35b6f987d8b < 381a0925c556a8d91a80a9b9e3e86651d60ffee3
• Linux d6ef8bb00aa65eceb413fc165a55086459863e38
• Linux 0e77f979a97d3d517fad0b51249ba6fb8ae2d365
• Linux 0782c8c7f80c9dd457acdfe16fd0f339f0e73093
• Linux 3719acc161d5c1ce09912cc1c9eddc2c5faa3c66
• Linux ff29fe26ab8679bc13a3f0bf5b2911535a1cfc35
• Linux f2f856b65ac4b77049c76c0e89ecd3a177e9fcd1
• Linux 75dd00b755ebfa9b24eaedc9f42e9adfc00ae00c
• Linux >= 4.4.281 < 4.5
• Linux >= 4.9.280 < 4.10
• Linux >= 4.14.244 < 4.15
• Linux >= 4.19.203 < 4.20
• Linux >= 5.4.140 < 5.5
• Linux >= 5.10.58 < 5.11
• Linux >= 5.13.10 < 5.14
• Linux 5.14

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.