[PATCH] clk: cdce925: Size the PLL child name buffer for any int

[PATCH] clk: cdce925: Size the PLL child name buffer for any int

[Jerome Brunet]

The PLL child node name is built from "PLL%d" in a 6 byte stack buffer.
The PLL index is bounded by the chip's num_plls, at most 4, but GCC
cannot see that bound and, with W=1, warns that the formatted string
may not fit.

Make the buffer large enough to hold any int and use snprintf() with
sizeof() so the size stays tied to the declaration.

Fixes: 19fbbbbcd3a3 ("Add TI CDCE925 I2C controlled clock synthesizer driver")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
 drivers/clk/clk-cdce925.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk-cdce925.c b/drivers/clk/clk-cdce925.c
index 4d49cc1659c0..56b69d4fe4c2 100644
--- a/drivers/clk/clk-cdce925.c
+++ b/drivers/clk/clk-cdce925.c
@@ -625,7 +625,12 @@ static int cdce925_probe(struct i2c_client *client)
 	int i;
 	int err;
 	struct device_node *np_output;
-	char child_name[6];
+	/*
+	 * The PLL number isn't a compile time constant so GCC can't infer
+	 * the number. Make the stack buffer large enough to hold any int
+	 * so Wformat-truncation does not complain.
+	 */
+	char child_name[15];
 	struct regmap_config config = {
 		.name = "configuration0",
 		.reg_bits = 8,
@@ -697,7 +702,7 @@ static int cdce925_probe(struct i2c_client *client)
 			dev_err(&client->dev, "Failed register PLL %d\n", i);
 			goto error;
 		}
-		sprintf(child_name, "PLL%d", i+1);
+		snprintf(child_name, sizeof(child_name), "PLL%d", i + 1);
 		np_output = of_get_child_by_name(node, child_name);
 		if (!np_output)
 			continue;

---
base-commit: a5929cbf1406eb3da217d4a182ff6c5b73f3ed91
base-tree: git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git clk-next
change-id: 20261014-cdce925-truncate-child-name-a4d9db9cf003

Best regards,
--  
Jerome

Re: [PATCH] clk: cdce925: Size the PLL child name buffer for any int

[Brian Masney]

On Wed, 14 Oct 2026 18:11:53 +0200, Jerome Brunet wrote:
> clk: cdce925: Size the PLL child name buffer for any int

Applied, thanks!

[1/1] clk: cdce925: Size the PLL child name buffer for any int
      commit: bca4927f760a77cd59f394b0b201f48c48e402c8

Best regards,
-- 
Brian Masney <masneyb@kernel.org>

Re: [PATCH] clk: cdce925: Size the PLL child name buffer for any int

[Jerome Brunet]

On jeu. 15 oct. 2026 at 11:18, Mike Looijmans <mike.looijmans@topic.nl> wrote:

> Met vriendelijke groet / kind regards,
>
> Mike Looijmans
> System Expert
>
> [cid:topic_3fa16e61-8444-4c42-bbdd-4da663de69ef.png]
> TOPIC Embedded Products B.V.
> Materiaalweg 4
> 5681 RJ Best    T:      +31 (0) 499 33 69 69
> The Netherlands E:      mike.looijmans@topic.nl<mailto:mike.looijmans@topic.nl>
>         W:      www.topic.nl<http://www.topic.nl>
>         L:      LinkedIn<https://www.linkedin.com/company/topic-embedded-systems>
>
> Please consider the environment before printing this e-mail
>
> On 10/14/26 18:11, Jerome Brunet wrote:
>
> The PLL child node name is built from "PLL%d" in a 6 byte stack buffer.
> The PLL index is bounded by the chip's num_plls, at most 4, but GCC
> cannot see that bound and, with W=1, warns that the formatted string
> may not fit.
>
> Make the buffer large enough to hold any int and use snprintf() with
> sizeof() so the size stays tied to the declaration.
>
> Fixes: 19fbbbbcd3a3 ("Add TI CDCE925 I2C controlled clock synthesizer driver")
> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com><mailto:jbrunet@baylibre.com>
> ---
>  drivers/clk/clk-cdce925.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clk-cdce925.c b/drivers/clk/clk-cdce925.c
> index 4d49cc1659c0..56b69d4fe4c2 100644
> --- a/drivers/clk/clk-cdce925.c
> +++ b/drivers/clk/clk-cdce925.c
> @@ -625,7 +625,12 @@ static int cdce925_probe(struct i2c_client *client)
>         int i;
>         int err;
>         struct device_node *np_output;
> -       char child_name[6];
> +       /*
> +        * The PLL number isn't a compile time constant so GCC can't infer
> +        * the number. Make the stack buffer large enough to hold any int
> +        * so Wformat-truncation does not complain.
> +        */
> +       char child_name[15];
>         struct regmap_config config = {
>                 .name = "configuration0",
>                 .reg_bits = 8,
> @@ -697,7 +702,7 @@ static int cdce925_probe(struct i2c_client *client)
>                         dev_err(&client->dev, "Failed register PLL %d\n", i);
>                         goto error;
>                 }
> -               sprintf(child_name, "PLL%d", i+1);
> +               snprintf(child_name, sizeof(child_name), "PLL%d", i + 1);
>
> This would also avoid the warning, without using a larger stack:
>
> sprintf(child_name, "PLL%c", i + '1');
>

If you keep snprintf and properly cast i, possibly.
Feel free to send a follow-up change.

NOTE: please reply to PATCHes using plain text emails.

>
>
>
>                 np_output = of_get_child_by_name(node, child_name);
>                 if (!np_output)
>                         continue;
>
> ---
> base-commit: a5929cbf1406eb3da217d4a182ff6c5b73f3ed91
> base-tree: git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git clk-next
> change-id: 20261014-cdce925-truncate-child-name-a4d9db9cf003
>
> Best regards,
> --
> Jerome
>
>
>

-- 
Jerome