linux-kernel - Re: [PATCH] drm: Add check for encoder in intel_get_crtc_new

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Message-ID: <87tte545pc.fsf@intel.com>
Date: Tue, 24 Sep 2024 15:05:51 +0300
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: George Rurikov <g.ryurikov@...uritycode.ru>
Cc: George Rurikov <g.ryurikov@...uritycode.ru>, Rodrigo Vivi
 <rodrigo.vivi@...el.com>, Joonas Lahtinen
 <joonas.lahtinen@...ux.intel.com>, Tvrtko Ursulin <tursulin@...ulin.net>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 intel-gfx@...ts.freedesktop.org, intel-xe@...ts.freedesktop.org,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH] drm: Add check for encoder in intel_get_crtc_new_encoder()

On Tue, 24 Sep 2024, George Rurikov <g.ryurikov@...uritycode.ru> wrote:
> If the video card driver could not find the connector assigned to the
> current video controller, or if the hardware status has changed so that
> a pre-existing connector is no longer active, none of the state
> connectors will meet the assignment criteria for the current crtc video
> controller.
>
> In the drm_WARN function, encoder->base.dev is called, so
> '&encoder->base.dev' will be dereferenced since encoder will still be
> initialized NULL.

encoder is not dereferenced there.

> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: e12d6218fda2 ("drm/i915: Reduce bigjoiner special casing")
> Cc: stable@...r.kernel.org
> Signed-off-by: George Rurikov <g.ryurikov@...uritycode.ru>
> ---
>  drivers/gpu/drm/i915/display/intel_display.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index b4ef4d59da1a..1f25b12e5f67 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -819,9 +819,11 @@ intel_get_crtc_new_encoder(const struct intel_atomic_state *state,
>                 num_encoders++;
>         }
>
> -       drm_WARN(state->base.dev, num_encoders != 1,
> +       if (encoder) {
> +               drm_WARN(state->base.dev, num_encoders != 1,
>                  "%d encoders for pipe %c\n",
>                  num_encoders, pipe_name(primary_crtc->pipe));
> +       }
>
>         return encoder;
>  }
> --
> 2.34.1
>
> Заявление о конфиденциальности
>
> Данное электронное письмо и любые приложения к нему являются конфиденциальными и предназначены исключительно для адресата. Если Вы не являетесь адресатом данного письма, пожалуйста, уведомите немедленно отправителя, не раскрывайте содержание другим лицам, не используйте его в каких-либо целях, не храните и не копируйте информацию любым способом.

Sorry, we can't accept patches with that boilerplate anyway.

BR,
Jani.


-- 
Jani Nikula, Intel