From: Sudeep Holla sudeep.holla@arm.com

[ 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.

Cc: stable@vger.kernel.org # v4.19+ Link: https://lore.kernel.org/r/20210624095059.4010157-2-sudeep.holla@arm.com Fixes: 933c504424a2 ("firmware: arm_scmi: add scmi protocol bus to enumerate protocol devices") Reported-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Tested-by: Cristian Marussi cristian.marussi@arm.com Reviewed-by: Cristian Marussi cristian.marussi@arm.com Acked-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Signed-off-by: Sudeep Holla sudeep.holla@arm.com --- Upstream commit 5e469dac326555d2038d199a6329458cc82a34e5 has been already applied to stable/linux-5.13.y, this is a backport with conflicts resolved for v4.19, v5.4 and v5.10. (SCMI stack did not even exist before 4.19) --- 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 7a30952b463d..66d445b14e51 100644 --- a/drivers/firmware/arm_scmi/bus.c +++ b/drivers/firmware/arm_scmi/bus.c @@ -100,6 +100,9 @@ int scmi_driver_register(struct scmi_driver *driver, struct module *owner, { int retval;

+ if (!driver->probe) + return -EINVAL; + driver->driver.bus = &scmi_bus_type; driver->driver.name = driver->name; driver->driver.owner = owner;