On Sat, 23 Sep 2023, Kees Cook wrote: > On Fri, Sep 22, 2023 at 03:27:17PM +0000, Justin Stitt wrote: > > `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@xxxxxxxxxxxxxxx > > Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx> > > --- > > 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); > > Given my desire to use sizeof(dest) for these things, I wonder if it'd > be nicer to pass more context here for the compiler as the only user of > this function is the immediately next function. Instead of passing in > "char *dest", it could pass "struct lp3952_led_array *priv", and > suddenly sizeof() would be possible. > > But, since it's technically correct as-is: > > struct lp3952_ctrl_hdl { > struct led_classdev cdev; > char name[LP3952_LABEL_MAX_LEN]; > > There's no pressing need to actually do the priv refactor. It's just a > comment on the coding style of the original code. :) > > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> I've applied this as-is, but please consider Kees' proposal. -- Lee Jones [李琼斯]
