When using HCI_UART_INIT_PENDING, hci_register_dev is not called from hci_uart_register_device. Instead, it is called by hci_uart_init_work, which is enqueued by hci_uart_init_ready (as hu->init_ready). In the case of the hci_h5 proto, hci_uart_init_ready is called only after handshaking with the hardware. If that handshake never completes, hci_register_dev is never called. When later unregistering the device, the kernel crashes:
Unable to handle kernel write to read-only memory at virtual address 0000000000000008 Internal error: Oops: 96000045 [#1] PREEMPT SMP Modules linked in: hci_uart(-) btrtl bnep bluetooth 8723cs(C) [...] CPU: 3 PID: 516 Comm: rmmod Tainted: G C 5.8.0-rc7-00277-gd87641cb644c-dirty #1 Hardware name: Pine64 PinePhone Braveheart (1.1) (DT) pstate: 80400005 (Nzcv daif +PAN -UAO BTYPE=--) pc : hci_unregister_dev+0x58/0x4b0 [bluetooth] lr : hci_unregister_dev+0x54/0x4b0 [bluetooth] sp : ffffffc011b5bc60 x29: ffffffc011b5bc60 x28: ffffff8075d23800 x27: 0000000000000000 x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 x23: 0000000000000000 x22: ffffffc008d86000 x21: ffffff8079dd2000 x20: ffffff8078026000 x19: ffffffc008f4f6d0 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000004 x14: ffffff807b15c110 x13: 0000000000000000 x12: ffffff80778e6720 x11: ffffff80778e66c8 x10: ffffff807ac6ada2 x9 : ffffffc010c95864 x8 : 0000000000210d00 x7 : 0000000000000000 x6 : 0000000000000001 x5 : 0000000000000001 x4 : 0000000000000001 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000 Call trace: hci_unregister_dev+0x58/0x4b0 [bluetooth] hci_uart_unregister_device+0x40/0x74 [hci_uart] h5_serdev_remove+0x18/0x20 [hci_uart] serdev_drv_remove+0x28/0x4c __device_release_driver+0x174/0x210 driver_detach+0xc4/0x100 bus_remove_driver+0x5c/0xb0 driver_unregister+0x34/0x60 h5_deinit+0x14/0xd10 [hci_uart] hci_uart_exit+0xc/0x30 [hci_uart] __arm64_sys_delete_module+0x1b0/0x260 el0_svc_common.constprop.0+0x60/0x100 do_el0_svc+0x20/0x30 el0_sync_handler+0x88/0x1b4 el0_sync+0x138/0x140 Code: aa1303e0 79408297 95f69770 a9400682 (f9000441) ---[ end trace b68f9044c8f92379 ]---
Fix the crash by flushing the hu->init_ready work to ensure hci_register_dev is not being called concurrently, and then only calling hci_unregister_dev if the HCI was previously registered.
Cc: stable@vger.kernel.org Fixes: fdee6d8fc630 ("Bluetooth: hci_serdev: Fix HCI_UART_INIT_PENDING not working") Signed-off-by: Samuel Holland samuel@sholland.org --- drivers/bluetooth/hci_serdev.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/bluetooth/hci_serdev.c b/drivers/bluetooth/hci_serdev.c index 599855e4c57c..3977bba485c2 100644 --- a/drivers/bluetooth/hci_serdev.c +++ b/drivers/bluetooth/hci_serdev.c @@ -355,7 +355,10 @@ void hci_uart_unregister_device(struct hci_uart *hu) struct hci_dev *hdev = hu->hdev;
clear_bit(HCI_UART_PROTO_READY, &hu->flags); - hci_unregister_dev(hdev); + + cancel_work_sync(&hu->init_ready); + if (test_bit(HCI_UART_REGISTERED, &hu->flags)) + hci_unregister_dev(hdev); hci_free_dev(hdev);
cancel_work_sync(&hu->write_work);