On 8/20/2021 15:44, Matthew Brost wrote:
Set number of engines before attempting to create contexts so the
function free_engines can clean up properly.

Fixes: d4433c7600f7 ("drm/i915/gem: Use the proto-context to handle create 
parameters (v5)")
Signed-off-by: Matthew Brost <matthew.br...@intel.com>
Cc: <sta...@vger.kernel.org>
---
  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 dbaeb924a437..bcaaf514876b 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -944,6 +944,7 @@ static struct i915_gem_engines *user_engines(struct 
i915_gem_context *ctx,
        unsigned int n;
e = alloc_engines(num_engines);
This can return null when out of memory. There needs to be an early exit check before dereferencing a null pointer. Not sure if that is a worse bug or not than leaking memory! Either way, it would be good to fix that too.

John.

+       e->num_engines = num_engines;
        for (n = 0; n < num_engines; n++) {
                struct intel_context *ce;
                int ret;
@@ -977,7 +978,6 @@ static struct i915_gem_engines *user_engines(struct 
i915_gem_context *ctx,
                        goto free_engines;
                }
        }
-       e->num_engines = num_engines;
return e;

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