From: Colin Ian King <colin.king@canonical.com>
Date: Fri, 8 Sep 2017 15:13:33 +0100
Subject: drm/amdkfd: check for null dev to avoid a null pointer dereference
Git-commit: bfaa1ce809bbcd12b1399409ab1dbf0cdaba6e27
Patch-mainline: v4.14-rc3
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

The call to kfd_device_by_id can potentially return null, so check that
dev is null and return with -EINVAL to avoid a null pointer dereference.

Detected by CoverityScan CID#1454629 ("Dereference null return value")

Fixes: 5d71dbc3a588 ("drm/amdkfd: Implement image tiling mode support v2")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -892,6 +892,8 @@ static int kfd_ioctl_get_tile_config(str
 	int err = 0;
 
 	dev = kfd_device_by_id(args->gpu_id);
+	if (!dev)
+		return -EINVAL;
 
 	dev->kfd2kgd->get_tile_config(dev->kgd, &config);