The dell_uart_bl_serdev_probe() function calls devm_serdev_device_open()
before setting the client ops via serdev_device_set_client_ops(). This
ordering can trigger a NULL pointer dereference in the serdev controller's
receive_buf handler, as it assumes serdev->ops is valid when
SERPORT_ACTIVE is set.
This is similar to the issue fixed in commit 5e700b384ec1
("platform/chrome: cros_ec_uart: properly fix race condition") where
devm_serdev_device_open() was called before fully initializing the
device.
Fix the race by ensuring client ops are set before enabling the port via
devm_serdev_device_open().
Fixes: 484bae9e4d6a ("platform/x86: Add new Dell UART backlight driver")
Signed-off-by: Chenyuan Yang <chenyuan0y@xxxxxxxxx>
---
drivers/platform/x86/dell/dell-uart-backlight.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/platform/x86/dell/dell-uart-backlight.c b/drivers/platform/x86/dell/dell-uart-backlight.c
index 6e5dc7e3674f..41162ff1686b 100644
--- a/drivers/platform/x86/dell/dell-uart-backlight.c
+++ b/drivers/platform/x86/dell/dell-uart-backlight.c
@@ -283,16 +283,16 @@ static int dell_uart_bl_serdev_probe(struct serdev_device *serdev)
init_waitqueue_head(&dell_bl->wait_queue);
dell_bl->dev = dev;
- ret = devm_serdev_device_open(dev, serdev);
- if (ret)
- return dev_err_probe(dev, ret, "opening UART device\n");
-
/* 9600 bps, no flow control, these are the default but set them to be sure */
serdev_device_set_baudrate(serdev, 9600);
serdev_device_set_flow_control(serdev, false);
serdev_device_set_drvdata(serdev, dell_bl);
serdev_device_set_client_ops(serdev, &dell_uart_bl_serdev_ops);
+ ret = devm_serdev_device_open(dev, serdev);
+ if (ret)
+ return dev_err_probe(dev, ret, "opening UART device\n");
+
get_version[0] = DELL_SOF(GET_CMD_LEN);
get_version[1] = CMD_GET_VERSION;
get_version[2] = dell_uart_checksum(get_version, 2);
--
2.34.1
