[PATCH v2] drm/i915: Prevent potential null-ptr-deref in engine_init_common

[Nirmoy Das]

This now merged. CI errors are unrelated.

On 10/11/2023 2:25 PM, Nirmoy Das wrote:
> 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 at intel.com>
> Cc: Andi Shyti <andi.shyti at linux.intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Signed-off-by: Nirmoy Das <nirmoy.das at intel.com>
> ---
>   drivers/gpu/drm/i915/gt/intel_engine_cs.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> index 179d9546865b..4a11219e560e 100644
> --- 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;