[PATCH] drm/i915/gt: Delete sysfs entries for engines on driver unload

[Krzysztof Niemiec <krzysztof.niemiec@xxxxxxxxx>]

While the sysfs entries for engines are added in intel_engines_init()
during driver load, the corresponding function intel_engines_release()
does not correctly get rid of them. This can lead to a UAF if, after
failed initialization (for example when gt is set wedged on init), we
try to access the engines.

Empty the engines llist in intel_engines_release().

Suggested-by: Chris Wilson <chris.p.wilson@xxxxxxxxxxxxxxx>
Signed-off-by: Krzysztof Niemiec <krzysztof.niemiec@xxxxxxxxx>
---
 drivers/gpu/drm/i915/gt/intel_engine_cs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 3b740ca25000..4d30a86016f2 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -693,6 +693,8 @@ void intel_engines_release(struct intel_gt *gt)
 
 		memset(&engine->reset, 0, sizeof(engine->reset));
 	}
+
+	llist_del_all(&gt->i915->uabi_engines_llist);
 }
 
 void intel_engine_free_request_pool(struct intel_engine_cs *engine)
-- 
2.45.2