[PATCH 0/2] drm: Make sure clk_init_data is fully initialized

[PATCH 0/2] drm: Make sure clk_init_data is fully initialized

[Geert Uytterhoeven]

	Hi all,

The clk_init_data structure contains several mutually-exclusive members
for different methods to specify the possible parents of a clock,
prompting drivers to initialize only the members they need.  However,
not initializing all members may cause subtle issues, which are only
exposed when CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_NONE is
enabled.

Hence this series aims to make sure all members are fully initialized,
to avoid such bugs, and to prevent future breakage when converting
drivers to a different method for specifying the parents.

Part One[1] fixed all cases that I identified to be real bugs, in
response to a crash I saw on BeagleBone Black.

This series is the DRM subpart of Part Two, which fixes remaining cases
that are currently harmless.  These are still fragile, and may cause
future breakage when converting drivers to a different method for
specifying the parents.

Thanks for your comments!

[1] "[PATCH treewide 0/5] clk: Make sure clk_init_data is fully
     initialized (part 1)"
    https://lore.kernel.org/cover.1787165329.git.geert+renesas@glider.be

Geert Uytterhoeven (2):
  drm/sun4i: Make sure clk_init_data is fully initialized
  drm/tegra: Make sure clk_init_data is fully initialized

 drivers/gpu/drm/sun4i/sun4i_hdmi_ddc_clk.c  | 2 +-
 drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 2 +-
 drivers/gpu/drm/sun4i/sun4i_tcon_dclk.c     | 2 +-
 drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c  | 2 +-
 drivers/gpu/drm/tegra/sor.c                 | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

-- 
2.43.0

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

[PATCH 1/2] drm/sun4i: Make sure clk_init_data is fully initialized

[Geert Uytterhoeven]

The clk_init_data structure contains several mutually-exclusive members
for different methods to specify the possible parents of a clock,
prompting drivers to initialize only the members they need.  However,
not initializing all members may cause subtle issues, which are only
exposed when CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_NONE is
enabled.

Make sure all members are fully initialized, to avoid such bugs, and to
prevent future breakage when converting drivers to a different method
for specifying the parents.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Compile-tested only.
---
 drivers/gpu/drm/sun4i/sun4i_hdmi_ddc_clk.c  | 2 +-
 drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 2 +-
 drivers/gpu/drm/sun4i/sun4i_tcon_dclk.c     | 2 +-
 drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c  | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_ddc_clk.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_ddc_clk.c
index b1beadb9bb59f8ff..958099d137f8df9b 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_ddc_clk.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_ddc_clk.c
@@ -109,7 +109,7 @@ static const struct clk_ops sun4i_ddc_ops = {
 
 int sun4i_ddc_create(struct sun4i_hdmi *hdmi, struct clk *parent)
 {
-	struct clk_init_data init;
+	struct clk_init_data init = {};
 	struct sun4i_ddc *ddc;
 	const char *parent_name;
 
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
index fbf7da9d9592141b..15b09d5479d97aa3 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
@@ -202,7 +202,7 @@ static const struct clk_ops sun4i_tmds_ops = {
 
 int sun4i_tmds_create(struct sun4i_hdmi *hdmi)
 {
-	struct clk_init_data init;
+	struct clk_init_data init = {};
 	struct sun4i_tmds *tmds;
 	const char *parents[2];
 
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon_dclk.c b/drivers/gpu/drm/sun4i/sun4i_tcon_dclk.c
index 4afb12bd5281f0d1..bdac1d622cc41351 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon_dclk.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon_dclk.c
@@ -167,7 +167,7 @@ static const struct clk_ops sun4i_dclk_ops = {
 int sun4i_dclk_create(struct device *dev, struct sun4i_tcon *tcon)
 {
 	const char *clk_name, *parent_name;
-	struct clk_init_data init;
+	struct clk_init_data init = {};
 	struct sun4i_dclk *dclk;
 	int ret;
 
diff --git a/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c b/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c
index a4d31fe3abff1ab1..bd0dba95421b3d8e 100644
--- a/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c
+++ b/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c
@@ -143,7 +143,7 @@ static const struct clk_ops sun8i_phy_clk_ops = {
 int sun8i_phy_clk_create(struct sun8i_hdmi_phy *phy, struct device *dev,
 			 bool second_parent)
 {
-	struct clk_init_data init;
+	struct clk_init_data init = {};
 	struct sun8i_phy_clk *priv;
 	const char *parents[2];
 
-- 
2.43.0

[PATCH 2/2] drm/tegra: Make sure clk_init_data is fully initialized

[Geert Uytterhoeven]

The clk_init_data structure contains several mutually-exclusive members
for different methods to specify the possible parents of a clock,
prompting drivers to initialize only the members they need.  However,
not initializing all members may cause subtle issues, which are only
exposed when CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_NONE is
enabled.

Make sure all members are fully initialized, to avoid such bugs, and to
prevent future breakage when converting drivers to a different method
for specifying the parents.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Compile-tested only.
---
 drivers/gpu/drm/tegra/sor.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c
index e384cbd0cbf72fb9..46449c69807d369e 100644
--- a/drivers/gpu/drm/tegra/sor.c
+++ b/drivers/gpu/drm/tegra/sor.c
@@ -600,8 +600,8 @@ static const struct clk_ops tegra_clk_sor_pad_ops = {
 static struct clk *tegra_clk_sor_pad_register(struct tegra_sor *sor,
 					      const char *name)
 {
+	struct clk_init_data init = {};
 	struct tegra_clk_sor_pad *pad;
-	struct clk_init_data init;
 	struct clk *clk;
 
 	pad = devm_kzalloc(sor->dev, sizeof(*pad), GFP_KERNEL);
-- 
2.43.0

Re: [PATCH 1/2] drm/sun4i: Make sure clk_init_data is fully initialized

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Resource leak and duplicate registration failure due to misuse of `devm_` APIs against an external device in a component `.bind` callback.
--

--- Patch [1]: [PATCH 1/2] drm/sun4i: Make sure clk_init_data is fully initialized ---
commit c10328b2f0b88fab02ca03cdd9ba8cea5c03c556
Author: Geert Uytterhoeven <geert+renesas@glider.be>

drm/sun4i: Make sure clk_init_data is fully initialized

This commit zero-initializes the clk_init_data structure to ensure all
members are fully initialized. This prevents subtle issues when only
some mutually-exclusive members are set, especially under certain stack
initialization configs.

[ ... ]

> diff --git a/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c b/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c
> index a4d31fe3abff1..bd0dba95421b3 100644
> --- a/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c
> +++ b/drivers/gpu/drm/sun4i/sun8i_hdmi_phy_clk.c
> @@ -143,7 +143,7 @@ static const struct clk_ops sun8i_phy_clk_ops = {
>  int sun8i_phy_clk_create(struct sun8i_hdmi_phy *phy, struct device *dev,
>  			 bool second_parent)
>  {
> -	struct clk_init_data init;
> +	struct clk_init_data init = {};
>  	struct sun8i_phy_clk *priv;
>  	const char *parents[2];
>  

[Severity: High]
This isn't a bug introduced by this patch, but I noticed a potential problem
with resource lifetimes in this function.

During the component bind phase, this code uses devm_kzalloc() and
devm_clk_register() against the external PHY platform device:

sun8i_phy_clk_create() {
    ...
	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
    ...
	phy->clk_phy = devm_clk_register(dev, &priv->hw);
    ...
}

Because the devres group is attached to the external PHY device (`dev`) rather
than the component device, it escapes the component unbind cycle.

When the HDMI component is unbound and re-bound, sun8i_phy_clk_create() runs
again. Will this permanently leak the memory allocated for `priv`?

Furthermore, will devm_clk_register() fail with -EEXIST on the second bind
since the previous clock was never unregistered?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/cover.1787239944.git.geert+renesas@glider.be?part=1

Re: [PATCH 2/2] drm/tegra: Make sure clk_init_data is fully initialized

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Missing bounds check on the `nvidia,interface` device tree property causes out-of-bounds array indexing and arbitrary MMIO access.
--

--- Patch [2]: [PATCH 2/2] drm/tegra: Make sure clk_init_data is fully initialized ---
commit d6e18a3c09cc145658765914a32b191ad5da6aa8
Author: Geert Uytterhoeven <geert+renesas@glider.be>

drm/tegra: Make sure clk_init_data is fully initialized

The clk_init_data structure contains several mutually-exclusive members
for different methods to specify the possible parents of a clock,
prompting drivers to initialize only the members they need.  However,
not initializing all members may cause subtle issues, which are only
exposed when CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_NONE is
enabled. Make sure all members are fully initialized, to avoid such bugs,
and to prevent future breakage when converting drivers to a different
method for specifying the parents.

> diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c
> index 802d2db7007af..c28557d0c96e5 100644
> --- a/drivers/gpu/drm/tegra/sor.c
> +++ b/drivers/gpu/drm/tegra/sor.c
> @@ -596,8 +596,8 @@ static const struct clk_ops tegra_clk_sor_pad_ops = {
>  static struct clk *tegra_clk_sor_pad_register(struct tegra_sor *sor,
>  					      const char *name)
>  {
> +	struct clk_init_data init = {};
>  	struct tegra_clk_sor_pad *pad;
> -	struct clk_init_data init;
>  	struct clk *clk;
>  
>  	pad = devm_kzalloc(sor->dev, sizeof(*pad), GFP_KERNEL);

[ ... ]

>  	pad->sor = sor;
>  
>  	init.name = name;
>  	init.flags = 0;
>  	init.parent_names = tegra_clk_sor_pad_parents[sor->index];

[Severity: High]
This is a pre-existing issue, but can this out-of-bounds array indexing
occur if the Device Tree provides an invalid "nvidia,interface" value?

In tegra_sor_parse_dt(), the "nvidia,interface" property is read and
assigned directly to sor->index without any bounds checking:

drivers/gpu/drm/tegra/sor.c:tegra_sor_parse_dt() {
	...
	err = of_property_read_u32(np, "nvidia,interface", &value);
	if (err < 0)
		return err;

	sor->index = value;
	...
}

If a malformed Device Tree is provided, does using this unbounded sor->index to
access the tegra_clk_sor_pad_parents array lead to an out-of-bounds memory read?

It appears it could also cause arbitrary MMIO reads and writes when computing
register offsets using DC_DISP_CORE_SOR_SET_CONTROL(sor->index).

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/cover.1787239944.git.geert+renesas@glider.be?part=2

Re: [PATCH 1/2] drm/sun4i: Make sure clk_init_data is fully initialized

[Chen-Yu Tsai]

On Fri, Aug 21, 2026 at 6:03 PM Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
>
> The clk_init_data structure contains several mutually-exclusive members
> for different methods to specify the possible parents of a clock,
> prompting drivers to initialize only the members they need.  However,
> not initializing all members may cause subtle issues, which are only
> exposed when CONFIG_INIT_STACK_ALL_PATTERN or CONFIG_INIT_STACK_NONE is
> enabled.
>
> Make sure all members are fully initialized, to avoid such bugs, and to
> prevent future breakage when converting drivers to a different method
> for specifying the parents.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---

Acked-by: Chen-Yu Tsai <wens@kernel.org>