drm/i915: Prevent potential null-ptr-deref in engine_init_common

If measure_breadcrumb_dw() returns an error and bce isn't created,
this commit ensures that intel_engine_destroy_pinned_context()
is not called with a NULL bce.

v2: Fix the subject s/UAF/null-ptr-deref(Jani)

Fixes: b35274993680 ("drm/i915: Create a kernel context for GGTT updates")
Cc: Oak Zeng <oak.zeng@intel.com>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231011122547.7085-1-nirmoy.das@intel.com

diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 179d9546865b036a09baf15f8c2a4bae3ae7396e..4a11219e560e0847637ee61de145eaf5bb79fc05 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -1491,7 +1491,8 @@ static int engine_init_common(struct intel_engine_cs *engine)
        return 0;
 
 err_bce_context:
-       intel_engine_destroy_pinned_context(bce);
+       if (bce)
+               intel_engine_destroy_pinned_context(bce);
 err_ce_context:
        intel_engine_destroy_pinned_context(ce);
        return ret;