linux-kernel - [PATCH] drm/display/dp_mst: Replace all non-returning strlcpy with strscpy

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Date:   Mon, 22 May 2023 15:51:24 +0000
From:   Azeem Shaikh <azeemshaikh38@...il.com>
To:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>
Cc:     linux-hardening@...r.kernel.org,
        Azeem Shaikh <azeemshaikh38@...il.com>,
        linux-kernel@...r.kernel.org, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Jani Nikula <jani.nikula@...el.com>,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>, Sam Ravnborg <sam@...nborg.org>,
        Jim Cromie <jim.cromie@...il.com>,
        Khaled Almahallawy <khaled.almahallawy@...el.com>,
        Lyude Paul <lyude@...hat.com>, Wayne Lin <Wayne.Lin@....com>,
        Imre Deak <imre.deak@...el.com>,
        Alex Deucher <alexander.deucher@....com>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH] drm/display/dp_mst: Replace all non-returning strlcpy with strscpy

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().
No return values were used, so direct replacement is safe.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@...il.com>
---
 drivers/gpu/drm/display/drm_dp_helper.c       |    2 +-
 drivers/gpu/drm/display/drm_dp_mst_topology.c |    2 +-
 drivers/gpu/drm/drm_mipi_dsi.c                |    2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 16565a0a5da6..e6a78fd32380 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -2103,7 +2103,7 @@ int drm_dp_aux_register(struct drm_dp_aux *aux)
 	aux->ddc.owner = THIS_MODULE;
 	aux->ddc.dev.parent = aux->dev;
 
-	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
+	strscpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
 		sizeof(aux->ddc.name));
 
 	ret = drm_dp_aux_register_devnode(aux);
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 38dab76ae69e..8f7403149b2b 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -5702,7 +5702,7 @@ static int drm_dp_mst_register_i2c_bus(struct drm_dp_mst_port *port)
 	aux->ddc.dev.parent = parent_dev;
 	aux->ddc.dev.of_node = parent_dev->of_node;
 
-	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(parent_dev),
+	strscpy(aux->ddc.name, aux->name ? aux->name : dev_name(parent_dev),
 		sizeof(aux->ddc.name));
 
 	return i2c_add_adapter(&aux->ddc);
diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 3fd6c733ff4e..6252ac01e945 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -223,7 +223,7 @@ mipi_dsi_device_register_full(struct mipi_dsi_host *host,
 
 	device_set_node(&dsi->dev, of_fwnode_handle(info->node));
 	dsi->channel = info->channel;
-	strlcpy(dsi->name, info->type, sizeof(dsi->name));
+	strscpy(dsi->name, info->type, sizeof(dsi->name));
 
 	ret = mipi_dsi_device_add(dsi);
 	if (ret) {