linux-kernel - Re: [PATCH v2 0/3] drm/display: bridge_connector: get/put the stored bridges: fix NULL pointer regression

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Message-ID: <a2b72d27-9207-42e9-835a-5d55c419d96e@samsung.com>
Date: Fri, 17 Oct 2025 23:54:29 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Luca Ceresoli <luca.ceresoli@...tlin.com>, Naresh Kamboju
	<naresh.kamboju@...aro.org>, Andrzej Hajda <andrzej.hajda@...el.com>, Neil
	Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman
	<jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, Maarten
	Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
	<mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
	<airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Dmitry Baryshkov
	<dmitry.baryshkov@....qualcomm.com>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>, Thomas Petazzoni
	<thomas.petazzoni@...tlin.com>, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/3] drm/display: bridge_connector: get/put the
 stored bridges: fix NULL pointer regression

On 17.10.2025 18:15, Luca Ceresoli wrote:
> A patch of mine recently merged in drm-misc-next [1] has a NULL pointer
> deref regression (reported here [2] and here [3]). Being in lack of a quick
> fix, I sent a revert proposal [4].
>
> The revert proposal has no answers currenty, and in the meanwhile I have a
> patch that implements the original idea but without the same bug. So here's
> a v2 series with:
>
>   - the same revert patch
>   - the original patch but rewritten without the same bug (and even simpler)
>
> Also the re-written patch is now split in two for clarity because it was
> doing two somewhat different things.
>
> [1] https://lore.kernel.org/all/20250926-drm-bridge-alloc-getput-bridge-connector-v2-1-138b4bb70576@bootlin.com/
> [2] https://lore.kernel.org/lkml/336fbfdd-c424-490e-b5d1-8ee84043dc80@samsung.com/
> [3] https://lore.kernel.org/lkml/CA+G9fYuKHp3QgPKjgFY3TfkDdh5Vf=Ae5pCW+eU41Bu=D7th2g@mail.gmail.com/
> [4] https://lore.kernel.org/lkml/20251016-drm-bridge-alloc-getput-bridge-connector-fix-hdmi_cec-v1-1-81d6984c5361@bootlin.com/
>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>

Works fine on all boards in my test lab.

Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>

> ---
> Changes in v2:
> - No changes to the revert patch
> - Added the (corrected) patch introducing the same feature as the original
>    buggy patch, and also split it in two fir clarity
> - Link to v1: https://lore.kernel.org/r/20251016-drm-bridge-alloc-getput-bridge-connector-fix-hdmi_cec-v1-1-81d6984c5361@bootlin.com
>
> ---
> Luca Ceresoli (3):
>        Revert "drm/display: bridge_connector: get/put the stored bridges"
>        drm/display: bridge_connector: get/put the stored bridges
>        drm/display: bridge_connector: get/put the panel_bridge
>
>   drivers/gpu/drm/display/drm_bridge_connector.c | 92 +++++++++++---------------
>   1 file changed, 39 insertions(+), 53 deletions(-)
> ---
> base-commit: 84a0a3f014cda68ff10b8517d09e9f0c1cd942a2
> change-id: 20251016-drm-bridge-alloc-getput-bridge-connector-fix-hdmi_cec-9a429ddb48e2
>
> Best regards,

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland