From d8953c8326d87a337763ca547ad7db034a94ddb1 Mon Sep 17 00:00:00 2001 From: Tvrtko Ursulin Date: Fri, 16 Dec 2016 13:18:42 +0000 Subject: [PATCH] drm/i915: Fix use after free in logical_render_ring_init Commit 3b3f1650b1ca ("drm/i915: Allocate intel_engine_cs structure only for the enabled engines") introduced the dynanically allocated engine instances and created an potential use after free scenario in logical_render_ring_init where lrc_destroy_wa_ctx_obj could be called after the engine instance has been freed. This can only happen during engine setup/init error handling which luckily does not happen ever in practice. Fix is to not call lrc_destroy_wa_ctx_obj since it would have already been executed from the preceding engine cleanup. Signed-off-by: Tvrtko Ursulin Reported-by: Dan Carpenter Fixes: 3b3f1650b1ca ("drm/i915: Allocate intel_engine_cs structure only for the enabled engines") Cc: Chris Wilson Cc: Joonas Lahtinen Cc: Tvrtko Ursulin Cc: Daniel Vetter Cc: Jani Nikula Reviewed-by: Chris Wilson Link: http://patchwork.freedesktop.org/patch/msgid/1481894322-2145-1-git-send-email-tvrtko.ursulin@linux.intel.com (cherry picked from commit d038fc7e4fff14d6b026130007faef35cbf5e956) Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/intel_lrc.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 0a09024d6ca3..d4961fa20c73 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -1968,12 +1968,7 @@ int logical_render_ring_init(struct intel_engine_cs *engine) ret); } - ret = logical_ring_init(engine); - if (ret) { - lrc_destroy_wa_ctx_obj(engine); - } - - return ret; + return logical_ring_init(engine); } int logical_xcs_ring_init(struct intel_engine_cs *engine) -- 2.20.1