In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: Avoid potential use-after-free in hci_error_reset
While handling the HCI_EV_HARDWARE_ERROR event, if the underlying BT controller is not responding, the GPIO reset mechanism would free the hci_dev and lead to a use-after-free in hci_error_reset.
Heres the call trace observed on a ChromeOS device with Intel AX201: queue_work_on+0x3e/0x6c __hci_cmd_sync_sk+0x2ee/0x4c0 [bluetooth HASH:3b4a6] ? init_wait_entry+0x31/0x31 __hci_cmd_sync+0x16/0x20 [bluetooth <HASH:3b4a 6>] hci_error_reset+0x4f/0xa4 [bluetooth <HASH:3b4a 6>] process_one_work+0x1d8/0x33f worker_thread+0x21b/0x373 kthread+0x13a/0x152 ? pr_cont_work+0x54/0x54 ? kthread_blkcg+0x31/0x31 ret_from_fork+0x1f/0x30
This patch holds the reference count on the hci_dev while processing a HCI_EV_HARDWARE_ERROR event to avoid potential crash.