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 new_bus->id to be NUL-terminated but not NUL-padded based on its prior assignment through snprintf: | snprintf(new_bus->id, MII_BUS_ID_SIZE, "gpio-%x", bus_id); Due to this, 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@vger.kernel.org Signed-off-by: Justin Stitt <justinst...@google.com> --- Note: build-tested only. Found with: $ rg "strncpy\(" --- drivers/net/mdio/mdio-gpio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/mdio/mdio-gpio.c b/drivers/net/mdio/mdio-gpio.c index 0fb3c2de0845..a1718d646504 100644 --- a/drivers/net/mdio/mdio-gpio.c +++ b/drivers/net/mdio/mdio-gpio.c @@ -125,7 +125,7 @@ static struct mii_bus *mdio_gpio_bus_init(struct device *dev, if (bus_id != -1) snprintf(new_bus->id, MII_BUS_ID_SIZE, "gpio-%x", bus_id); else - strncpy(new_bus->id, "gpio", MII_BUS_ID_SIZE); + strscpy(new_bus->id, "gpio", sizeof(new_bus->id)); if (pdata) { new_bus->phy_mask = pdata->phy_mask; --- base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2 change-id: 20231012-strncpy-drivers-net-mdio-mdio-gpio-c-bddd9ed0c630 Best regards, -- Justin Stitt <justinst...@google.com>
