Re: [PATCH] drm/meson: fix device_node leak in meson_encoder_dsi_probe()

From: Neil Armstrong <neil.armstrong@linaro.org>
To: mileskrause5200@gmail.com,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Nicolas Belin <nbelin@baylibre.com>,
	Jagan Teki <jagan@amarulasolutions.com>
Cc: dri-devel@lists.freedesktop.org,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/meson: fix device_node leak in meson_encoder_dsi_probe()
Date: Thu, 10 Sep 2026 09:23:18 +0200	[thread overview]
Message-ID: <ca31e73c-09be-43fe-8904-8a813152c3ca@linaro.org> (raw)
In-Reply-To: <20260906-meson-dsi-of-node-leak-v1-1-9d183560279d@gmail.com>

On 9/6/26 21:43, Miles Krause via B4 Relay wrote:
> From: Miles Krause <mileskrause5200@gmail.com>
> 
> meson_encoder_dsi_probe() looks up the DSI transceiver's device node
> with of_graph_get_remote_node() and hands it to
> of_drm_find_and_get_bridge(), but never drops the reference that the
> lookup returned.
> 
> of_graph_get_remote_node() returns the node with its refcount
> incremented, and of_drm_find_and_get_bridge() takes its own reference
> on the bridge it finds, so 'remote' is leaked on every path once the
> lookup succeeds: on the -EPROBE_DEFER return taken when no bridge is
> found, and on a fully successful probe alike.
> 
> The two sibling encoders in this driver already handle this correctly.
> meson_encoder_cvbs_probe() calls of_node_put(remote) immediately after
> of_drm_find_and_get_bridge(), and meson_encoder_hdmi_probe() releases
> the node both on its error path and after of_find_device_by_node().
> 
> Release the reference in the same place meson_encoder_cvbs_probe()
> does, which covers both the error and the success path.
> 
> Fixes: 42dcf15f901c ("drm/meson: add DSI encoder")
> Signed-off-by: Miles Krause <mileskrause5200@gmail.com>
> ---
>   drivers/gpu/drm/meson/meson_encoder_dsi.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/meson/meson_encoder_dsi.c b/drivers/gpu/drm/meson/meson_encoder_dsi.c
> index 3e422b612f74..3fe604496294 100644
> --- a/drivers/gpu/drm/meson/meson_encoder_dsi.c
> +++ b/drivers/gpu/drm/meson/meson_encoder_dsi.c
> @@ -120,6 +120,7 @@ int meson_encoder_dsi_probe(struct meson_drm *priv)
>   	}
>   
>   	meson_encoder_dsi->bridge.next_bridge = of_drm_find_and_get_bridge(remote);
> +	of_node_put(remote);
>   	if (!meson_encoder_dsi->bridge.next_bridge)
>   		return dev_err_probe(priv->dev, -EPROBE_DEFER,
>   				     "Failed to find DSI transceiver bridge\n");
> 
> ---
> base-commit: 88405f0ad1d5c680afe3ea0ce9345fa9e1deaac8
> change-id: 20260906-meson-dsi-of-node-leak-744899da5712
> 
> Best regards,

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

Thanks,
Neil

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