[PATCH v1 1/2] arm_mpam: Fix a NULL pointer dereference on unbinding after an error interrupt

[Ben Horgan <ben.horgan@arm.com>]

If a user unbinds an MSC after mpam_disable() has been run in response
to an error interrupt then a dereference of a NULL pointer occurs as
mpam_disable() sets the drvdata to NULL. Add an early return to the driver
remove callback to avoid this.

Fixes: f04046f2577a ("arm_mpam: Add probe/remove for mpam msc driver and kbuild boiler plate")
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
---
 drivers/resctrl/mpam_devices.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 2f09f4b78bd3..bc6cc0b5c96b 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -2025,6 +2025,9 @@ static void mpam_msc_drv_remove(struct platform_device *pdev)
 {
 	struct mpam_msc *msc = platform_get_drvdata(pdev);
 
+	if (!msc)
+		return;
+
 	mutex_lock(&mpam_list_lock);
 	mpam_msc_destroy(msc);
 	mutex_unlock(&mpam_list_lock);
-- 
2.43.0