[PATCH v2] Bluetooth: qca: Fix crash when btattach BT controller QCA_ROME

[Zijun Hu <quic_zijuhu@quicinc.com>]

A crash will happen when use tool btattach to attach a BT controller
QCA_ROME, and it is caused by dereferencing nullptr hu->serdev, fixed
by null check before access.

sudo btattach -B /dev/ttyUSB0 -P qca
Bluetooth: hci1: QCA setup on UART is completed
BUG: kernel NULL pointer dereference, address: 00000000000002f0
......
Workqueue: hci1 hci_power_on [bluetooth]
RIP: 0010:qca_setup+0x7c1/0xe30 [hci_uart]
......
Call Trace:
 <TASK>
 ? show_regs+0x72/0x90
 ? __die+0x25/0x80
 ? page_fault_oops+0x154/0x4c0
 ? srso_alias_return_thunk+0x5/0xfbef5
 ? kmem_cache_alloc+0x16b/0x310
 ? do_user_addr_fault+0x330/0x6e0
 ? srso_alias_return_thunk+0x5/0xfbef5
 ? exc_page_fault+0x84/0x1b0
 ? asm_exc_page_fault+0x27/0x30
 ? qca_setup+0x7c1/0xe30 [hci_uart]
 hci_uart_setup+0x5c/0x1a0 [hci_uart]
 hci_dev_open_sync+0xee/0xca0 [bluetooth]
 hci_dev_do_open+0x2a/0x70 [bluetooth]
 hci_power_on+0x46/0x210 [bluetooth]
 process_one_work+0x17b/0x360
 worker_thread+0x307/0x430
 ? __pfx_worker_thread+0x10/0x10
 kthread+0xf7/0x130
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x46/0x70
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1b/0x30
 </TASK>

Fixes: 03b0093f7b31 ("Bluetooth: hci_qca: get wakeup status from serdev device handle")
Cc: <stable@vger.kernel.org>
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Tested-by: Zijun Hu <quic_zijuhu@quicinc.com>
---
Changes since v1:
 - Correct tile and commit message based on Paul's suggestions

 drivers/bluetooth/hci_qca.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index 94b8c406f0c0..6fcfc1f7bb12 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -1951,7 +1951,7 @@ static int qca_setup(struct hci_uart *hu)
 		qca_debugfs_init(hdev);
 		hu->hdev->hw_error = qca_hw_error;
 		hu->hdev->cmd_timeout = qca_cmd_timeout;
-		if (device_can_wakeup(hu->serdev->ctrl->dev.parent))
+		if (hu->serdev && device_can_wakeup(hu->serdev->ctrl->dev.parent))
 			hu->hdev->wakeup = qca_wakeup;
 	} else if (ret == -ENOENT) {
 		/* No patch/nvm-config found, run with original fw/config */
-- 
2.7.4