[PATCH 5.13 048/223] firmware: arm_scmi: Ensure drivers provide a probe function

From: Greg Kroah-Hartman
Date: Mon Jul 26 2021 - 12:27:20 EST

From: Sudeep Holla <sudeep.holla@xxxxxxx>

[ Upstream commit 5e469dac326555d2038d199a6329458cc82a34e5 ]

The bus probe callback calls the driver callback without further
checking. Better be safe than sorry and refuse registration of a driver
without a probe function to prevent a NULL pointer exception.

Link: https://lore.kernel.org/r/20210624095059.4010157-2-sudeep.holla@xxxxxxx
Fixes: 933c504424a2 ("firmware: arm_scmi: add scmi protocol bus to enumerate protocol devices")
Reported-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Tested-by: Cristian Marussi <cristian.marussi@xxxxxxx>
Reviewed-by: Cristian Marussi <cristian.marussi@xxxxxxx>
Acked-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/firmware/arm_scmi/bus.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 784cf0027da3..9184a0d5acbe 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -139,6 +139,9 @@ int scmi_driver_register(struct scmi_driver *driver, struct module *owner,
int retval;

+ if (!driver->probe)
+ return -EINVAL;
retval = scmi_protocol_device_request(driver->id_table);
if (retval)
return retval;