[PATCH v2] Bluetooth: hci_qca: Fix driver shutdown on closed serdev

[Krzysztof Kozlowski]

The driver shutdown callback (which sends EDL_SOC_RESET to the device
over serdev) should not be invoked when HCI device is not open (e.g. if
hci_dev_open_sync() failed), because the serdev and its TTY are not open
either.  Also skip this step if device is powered off
(qca_power_shutdown()).

The shutdown callback causes use-after-free during system reboot with
Qualcomm Atheros Bluetooth:

  Unable to handle kernel paging request at virtual address 0072662f67726fd7
  ...
  CPU: 6 PID: 1 Comm: systemd-shutdow Tainted: G        W          6.1.0-rt5-00325-g8a5f56bcfcca #8
  Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
  Call trace:
   tty_driver_flush_buffer+0x4/0x30
   serdev_device_write_flush+0x24/0x34
   qca_serdev_shutdown+0x80/0x130 [hci_uart]
   device_shutdown+0x15c/0x260
   kernel_restart+0x48/0xac

KASAN report:

  BUG: KASAN: use-after-free in tty_driver_flush_buffer+0x1c/0x50
  Read of size 8 at addr ffff16270c2e0018 by task systemd-shutdow/1

  CPU: 7 PID: 1 Comm: systemd-shutdow Not tainted 6.1.0-next-20221220-00014-gb85aaf97fb01-dirty #28
  Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
  Call trace:
   dump_backtrace.part.0+0xdc/0xf0
   show_stack+0x18/0x30
   dump_stack_lvl+0x68/0x84
   print_report+0x188/0x488
   kasan_report+0xa4/0xf0
   __asan_load8+0x80/0xac
   tty_driver_flush_buffer+0x1c/0x50
   ttyport_write_flush+0x34/0x44
   serdev_device_write_flush+0x48/0x60
   qca_serdev_shutdown+0x124/0x274
   device_shutdown+0x1e8/0x350
   kernel_restart+0x48/0xb0
   __do_sys_reboot+0x244/0x2d0
   __arm64_sys_reboot+0x54/0x70
   invoke_syscall+0x60/0x190
   el0_svc_common.constprop.0+0x7c/0x160
   do_el0_svc+0x44/0xf0
   el0_svc+0x2c/0x6c
   el0t_64_sync_handler+0xbc/0x140
   el0t_64_sync+0x190/0x194

Fixes: 7e7bbddd029b ("Bluetooth: hci_qca: Fix qca6390 enable failure after warm reboot")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>

---

Changes since v1:
1. Drop serdev patch and fix it only on BT side.
2. Update commit msg.
---
 drivers/bluetooth/hci_qca.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index bb7623fe53a8..157fc4d024c1 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -2166,10 +2166,16 @@ static void qca_serdev_shutdown(struct device *dev)
 	int timeout = msecs_to_jiffies(CMD_TRANS_TIMEOUT_MS);
 	struct serdev_device *serdev = to_serdev_device(dev);
 	struct qca_serdev *qcadev = serdev_device_get_drvdata(serdev);
+	struct hci_uart *hu = &qcadev->serdev_hu;
+	struct hci_dev *hdev = hu->hdev;
+	struct qca_data *qca = hu->priv;
 	const u8 ibs_wake_cmd[] = { 0xFD };
 	const u8 edl_reset_soc_cmd[] = { 0x01, 0x00, 0xFC, 0x01, 0x05 };
 
 	if (qcadev->btsoc_type == QCA_QCA6390) {
+		if (test_bit(QCA_BT_OFF, &qca->flags) || !test_bit(HCI_RUNNING, &hdev->flags))
+			return;
+
 		serdev_device_write_flush(serdev);
 		ret = serdev_device_write_buf(serdev, ibs_wake_cmd,
 					      sizeof(ibs_wake_cmd));
-- 
2.34.1