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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>,
        Cristian Marussi <cristian.marussi@arm.com>,
        Sudeep Holla <sudeep.holla@arm.com>
Subject: [PATCH 5.10 22/30] firmware: arm_scmi: Ensure drivers provide a probe function
Date:   Fri,  6 Aug 2021 10:17:00 +0200
Message-Id: <20210806081113.880138462@linuxfoundation.org>
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From: Sudeep Holla <sudeep.holla@arm.com>

commit 5e469dac326555d2038d199a6329458cc82a34e5 upstream.

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@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/firmware/arm_scmi/bus.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -113,6 +113,9 @@ int scmi_driver_register(struct scmi_dri
 {
 	int retval;
 
+	if (!driver->probe)
+		return -EINVAL;
+
 	driver->driver.bus = &scmi_bus_type;
 	driver->driver.name = driver->name;
 	driver->driver.owner = owner;