Re: [Intel-gfx] [PATCH v2] drm/i915/display: Fix a use-after-free when intel_edp_init_connector fails

[Jani Nikula <jani.nikula@intel.com>]

On Mon, 29 May 2023, Jani Nikula <jani.nikula@intel.com> wrote:
> From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>
> We enable the DP aux channel during probe, but may free the connector
> soon afterwards. Ensure the DP aux display power put (and any other
> async put for that matter) is completed before everything is freed, to
> prevent a use-after-free in icl_aux_pw_to_phy(), called from
> icl_combo_phy_aux_power_well_disable.
>
> v2 by Jani:
> - do a regular flush before freeing dig_port
>
> Cc: Imre Deak <imre.deak@intel.com>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>
> ---
>
> v2 of https://patchwork.freedesktop.org/patch/msgid/20221220094618.207126-1-maarten.lankhorst@linux.intel.com
>
> The encoder cleanup paths could use some cleanup and unification, but do
> what's needed here.

Pushed [1] instead, which I'd missed.

BR,
Jani.


[1] https://patchwork.freedesktop.org/patch/msgid/20221222201804.1380963-1-maarten.lankhorst@linux.intel.com


> ---
>  drivers/gpu/drm/i915/display/g4x_dp.c    | 2 ++
>  drivers/gpu/drm/i915/display/intel_ddi.c | 2 ++
>  2 files changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/g4x_dp.c b/drivers/gpu/drm/i915/display/g4x_dp.c
> index 112d91d81fdc..e8147c18fa93 100644
> --- a/drivers/gpu/drm/i915/display/g4x_dp.c
> +++ b/drivers/gpu/drm/i915/display/g4x_dp.c
> @@ -1379,6 +1379,8 @@ bool g4x_dp_init(struct drm_i915_private *dev_priv,
>  	return true;
>  
>  err_init_connector:
> +	/* aync put accesses the dig_port, ensure it's done before free */
> +	intel_display_power_flush_work(dev_priv);
>  	drm_encoder_cleanup(encoder);
>  err_encoder_init:
>  	kfree(intel_connector);
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index d1a9a3cf94b5..dfa1c44dc442 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -4971,6 +4971,8 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
>  	return;
>  
>  err:
> +	/* aync put accesses the dig_port, ensure it's done before free */
> +	intel_display_power_flush_work(dev_priv);
>  	drm_encoder_cleanup(&encoder->base);
>  	kfree(dig_port);
>  }

-- 
Jani Nikula, Intel Open Source Graphics Center