[PATCH] drm/i915: Fix possible uninitialized variable in parallel extension

[PATCH] drm/i915: Fix possible uninitialized variable in parallel extension

[Matthew Brost]

'prev_engine' was declared inside the output loop and checked in the
inner after at least 1 pass of either loop. The variable should be
declared outside both loops as it needs to be persistent across the
entire loop structure.

Fixes: e5e32171a2cf ("drm/i915/guc: Connect UAPI to GuC multi-lrc interface")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 347dab952e90..97d2ac22ae55 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -564,6 +564,7 @@ set_proto_ctx_engines_parallel_submit(struct i915_user_extension __user *base,
 		container_of_user(base, typeof(*ext), base);
 	const struct set_proto_ctx_engines *set = data;
 	struct drm_i915_private *i915 = set->i915;
+	struct i915_engine_class_instance prev_engine;
 	u64 flags;
 	int err = 0, n, i, j;
 	u16 slot, width, num_siblings;
@@ -629,7 +630,6 @@ set_proto_ctx_engines_parallel_submit(struct i915_user_extension __user *base,
 	/* Create contexts / engines */
 	for (i = 0; i < width; ++i) {
 		intel_engine_mask_t current_mask = 0;
-		struct i915_engine_class_instance prev_engine;
 
 		for (j = 0; j < num_siblings; ++j) {
 			struct i915_engine_class_instance ci;
-- 
2.33.1

Re: [PATCH] drm/i915: Fix possible uninitialized variable in parallel extension

[Lucas De Marchi]

On Sat, Dec 18, 2021 at 04:19:09PM -0800, Matthew Brost wrote:
>'prev_engine' was declared inside the output loop and checked in the
>inner after at least 1 pass of either loop. The variable should be
>declared outside both loops as it needs to be persistent across the
>entire loop structure.
>
>Fixes: e5e32171a2cf ("drm/i915/guc: Connect UAPI to GuC multi-lrc interface")
>Signed-off-by: Matthew Brost <matthew.brost@intel.com>


Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>

thanks
Lucas De Marchi