| Message ID | 20230922-strncpy-drivers-leds-leds-lp3952-c-v1-1-4941d6f60ca4@google.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | a337ee0d25ba24212269c2442981dc4fb5232a8c |
| Headers | show |
| Series | leds: lp3952: replace deprecated strncpy with strscpy | expand |
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@vger.kernel.org > Signed-off-by: Justin Stitt <justinstitt@google.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); 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@chromium.org> -Kees > return 0; > } > > > --- > base-commit: 2cf0f715623872823a72e451243bbf555d10d032 > change-id: 20230922-strncpy-drivers-leds-leds-lp3952-c-666fcfabeebd > > Best regards, > -- > Justin Stitt <justinstitt@google.com> >
On Fri, 22 Sep 2023 15:27:17 +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); > > [...] Applied, thanks! [1/1] leds: lp3952: replace deprecated strncpy with strscpy commit: 821d3ff4b4e2c689576a623348555114e3f2f1c2 -- Lee Jones [李琼斯]
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@vger.kernel.org > > Signed-off-by: Justin Stitt <justinstitt@google.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); > > 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@chromium.org> I've applied this as-is, but please consider Kees' proposal.
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; }
`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@vger.kernel.org Signed-off-by: Justin Stitt <justinstitt@google.com> --- Note: build-tested only. --- drivers/leds/leds-lp3952.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- base-commit: 2cf0f715623872823a72e451243bbf555d10d032 change-id: 20230922-strncpy-drivers-leds-leds-lp3952-c-666fcfabeebd Best regards, -- Justin Stitt <justinstitt@google.com>