[PATCH 3/3] drm/xe/vm: Clear the scratch_pt pointer on error

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

Avoid triggering a dereference of an error pointer on cleanup in
xe_vm_free_scratch() by clearing any scratch_pt error pointer.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Fixes: 06951c2ee72d ("drm/xe: Use NULL PTEs as scratch PTEs")
Cc: Brian Welty <brian.welty@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: <stable@vger.kernel.org> # v6.8+
Cc: Reviewed-by: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/xe/xe_vm.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index c86337e08a55..d3f6dc6b1779 100644
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -1635,8 +1635,12 @@ static int xe_vm_create_scratch(struct xe_device *xe, struct xe_tile *tile,
 
 	for (i = MAX_HUGEPTE_LEVEL; i < vm->pt_root[id]->level; i++) {
 		vm->scratch_pt[id][i] = xe_pt_create(vm, tile, i);
-		if (IS_ERR(vm->scratch_pt[id][i]))
-			return PTR_ERR(vm->scratch_pt[id][i]);
+		if (IS_ERR(vm->scratch_pt[id][i])) {
+			int err = PTR_ERR(vm->scratch_pt[id][i]);
+
+			vm->scratch_pt[id][i] = NULL;
+			return err;
+		}
 
 		xe_pt_populate_empty(tile, vm, vm->scratch_pt[id][i]);
 	}
-- 
2.50.1