linux-kernel - [PATCH] leds: lp3952: replace deprecated strncpy with strscpy

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Message-ID: <20230922-strncpy-drivers-leds-leds-lp3952-c-v1-1-4941d6f60ca4@google.com>
Date:   Fri, 22 Sep 2023 15:27:17 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org,
        Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] leds: lp3952: replace deprecated strncpy with strscpy

`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We expect `dest` to be NUL-terminated due to its use with dev_err.

lp3952_get_label()'s  dest argument is priv->leds[i].name:
|    acpi_ret = lp3952_get_label(&priv->client->dev, led_name_hdl[i],
|                                priv->leds[i].name);
... which is then assigned to:
|    priv->leds[i].cdev.name = priv->leds[i].name;
... which is used with a format string
|    dev_err(&priv->client->dev,
|            "couldn't register LED %s\n",
|            priv->leds[i].cdev.name);

There is no indication that NUL-padding is required but if it is let's
opt for strscpy_pad.

Considering the above, a suitable replacement is `strscpy` [2] due to
the fact that it guarantees NUL-termination on the destination buffer
without unnecessarily NUL-padding.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@...r.kernel.org
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Note: build-tested only.
---
 drivers/leds/leds-lp3952.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/leds/leds-lp3952.c b/drivers/leds/leds-lp3952.c
index 3bd55652a706..62ade3f05a87 100644
--- a/drivers/leds/leds-lp3952.c
+++ b/drivers/leds/leds-lp3952.c
@@ -101,7 +101,7 @@ static int lp3952_get_label(struct device *dev, const char *label, char *dest)
 	if (ret)
 		return ret;

-	strncpy(dest, str, LP3952_LABEL_MAX_LEN);
+	strscpy(dest, str, LP3952_LABEL_MAX_LEN);
 	return 0;
 }

---
base-commit: 2cf0f715623872823a72e451243bbf555d10d032
change-id: 20230922-strncpy-drivers-leds-leds-lp3952-c-666fcfabeebd

Best regards,
--
Justin Stitt <justinstitt@...gle.com>