`strncpy` is deprecated for use on NUL-terminated destination strings [1].
We should prefer more robust and less ambiguous string interfaces.
We expect adc->chan_name[val] to be NUL-terminated based on ch_name's
use within functions that expect NUL-terminated strings like strncmp and
printf-likes:
| if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) {
| /* Check internal channel availability */
| switch (i) {
| case STM32_ADC_INT_CH_VDDCORE:
| if (!adc->cfg->regs->or_vddcore.reg)
| dev_warn(&indio_dev->dev,
| "%s channel not available\n", ch_name);
...
There is no evidence that NUL-padding is needed either.
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. If, for any reason, NUL-padding _is_
required we should go for `strscpy_pad`.
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: [email protected]
Signed-off-by: Justin Stitt <[email protected]>
---
Note: build-tested
---
drivers/iio/adc/stm32-adc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index f7613efb870d..9cdcf396d901 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -2209,7 +2209,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
ret = -EINVAL;
goto err;
}
- strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
+ strscpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
ret = stm32_adc_populate_int_ch(indio_dev, name, val);
if (ret == -ENOENT)
continue;
---
base-commit: 2cf0f715623872823a72e451243bbf555d10d032
change-id: 20230921-strncpy-drivers-iio-adc-stm32-adc-c-1bf936a4ffbb
Best regards,
--
Justin Stitt <[email protected]>
On Thu, Sep 21, 2023 at 04:54:00AM +0000, Justin Stitt wrote:
> `strncpy` is deprecated for use on NUL-terminated destination strings [1].
>
> We should prefer more robust and less ambiguous string interfaces.
>
> We expect adc->chan_name[val] to be NUL-terminated based on ch_name's
> use within functions that expect NUL-terminated strings like strncmp and
> printf-likes:
> | if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) {
> | /* Check internal channel availability */
> | switch (i) {
> | case STM32_ADC_INT_CH_VDDCORE:
> | if (!adc->cfg->regs->or_vddcore.reg)
> | dev_warn(&indio_dev->dev,
> | "%s channel not available\n", ch_name);
> ...
>
> There is no evidence that NUL-padding is needed either.
Agreed -- it's used as a C string everywhere I can see.
>
> 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. If, for any reason, NUL-padding _is_
> required we should go for `strscpy_pad`.
>
> 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: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> Note: build-tested
> ---
> drivers/iio/adc/stm32-adc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index f7613efb870d..9cdcf396d901 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -2209,7 +2209,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
> ret = -EINVAL;
> goto err;
> }
> - strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
> + strscpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
I still prefer sizeof($dst), but yes, these are the same:
char chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
If this needs a v2, please improve the Subject, but it is technically
correct, so:
Reviewed-by: Kees Cook <[email protected]>
:)
-Kees
--
Kees Cook
On Sat, 23 Sep 2023 20:15:09 -0700
Kees Cook <[email protected]> wrote:
> On Thu, Sep 21, 2023 at 04:54:00AM +0000, Justin Stitt wrote:
> > `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> >
> > We should prefer more robust and less ambiguous string interfaces.
> >
> > We expect adc->chan_name[val] to be NUL-terminated based on ch_name's
> > use within functions that expect NUL-terminated strings like strncmp and
> > printf-likes:
> > | if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) {
> > | /* Check internal channel availability */
> > | switch (i) {
> > | case STM32_ADC_INT_CH_VDDCORE:
> > | if (!adc->cfg->regs->or_vddcore.reg)
> > | dev_warn(&indio_dev->dev,
> > | "%s channel not available\n", ch_name);
> > ...
> >
> > There is no evidence that NUL-padding is needed either.
>
> Agreed -- it's used as a C string everywhere I can see.
>
> >
> > 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. If, for any reason, NUL-padding _is_
> > required we should go for `strscpy_pad`.
> >
> > 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: [email protected]
> > Signed-off-by: Justin Stitt <[email protected]>
> > ---
> > Note: build-tested
> > ---
> > drivers/iio/adc/stm32-adc.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> > index f7613efb870d..9cdcf396d901 100644
> > --- a/drivers/iio/adc/stm32-adc.c
> > +++ b/drivers/iio/adc/stm32-adc.c
> > @@ -2209,7 +2209,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
> > ret = -EINVAL;
> > goto err;
> > }
> > - strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
> > + strscpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
>
> I still prefer sizeof($dst), but yes, these are the same:
>
> char chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
>
> If this needs a v2, please improve the Subject, but it is technically
> correct, so:
Hi Kees,
I can tweak the subject whilst applying. What did you have in mind
as a better one?
Jonathan
>
> Reviewed-by: Kees Cook <[email protected]>
>
> :)
>
> -Kees
>
On Sat, Sep 30, 2023 at 06:41:18PM +0100, Jonathan Cameron wrote:
> On Sat, 23 Sep 2023 20:15:09 -0700
> Kees Cook <[email protected]> wrote:
>
> > On Thu, Sep 21, 2023 at 04:54:00AM +0000, Justin Stitt wrote:
> > > `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> > >
> > > We should prefer more robust and less ambiguous string interfaces.
> > >
> > > We expect adc->chan_name[val] to be NUL-terminated based on ch_name's
> > > use within functions that expect NUL-terminated strings like strncmp and
> > > printf-likes:
> > > | if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) {
> > > | /* Check internal channel availability */
> > > | switch (i) {
> > > | case STM32_ADC_INT_CH_VDDCORE:
> > > | if (!adc->cfg->regs->or_vddcore.reg)
> > > | dev_warn(&indio_dev->dev,
> > > | "%s channel not available\n", ch_name);
> > > ...
> > >
> > > There is no evidence that NUL-padding is needed either.
> >
> > Agreed -- it's used as a C string everywhere I can see.
> >
> > >
> > > 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. If, for any reason, NUL-padding _is_
> > > required we should go for `strscpy_pad`.
> > >
> > > 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: [email protected]
> > > Signed-off-by: Justin Stitt <[email protected]>
> > > ---
> > > Note: build-tested
> > > ---
> > > drivers/iio/adc/stm32-adc.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> > > index f7613efb870d..9cdcf396d901 100644
> > > --- a/drivers/iio/adc/stm32-adc.c
> > > +++ b/drivers/iio/adc/stm32-adc.c
> > > @@ -2209,7 +2209,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
> > > ret = -EINVAL;
> > > goto err;
> > > }
> > > - strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
> > > + strscpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
> >
> > I still prefer sizeof($dst), but yes, these are the same:
> >
> > char chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
> >
> > If this needs a v2, please improve the Subject, but it is technically
> > correct, so:
>
> Hi Kees,
>
> I can tweak the subject whilst applying. What did you have in mind
> as a better one?
I would use "iio: adc: stm32-adc: Replace deprecated strncpy() with strscpy()"
Thanks!
-Kees
--
Kees Cook
On Sat, 30 Sep 2023 10:57:03 -0700
Kees Cook <[email protected]> wrote:
> On Sat, Sep 30, 2023 at 06:41:18PM +0100, Jonathan Cameron wrote:
> > On Sat, 23 Sep 2023 20:15:09 -0700
> > Kees Cook <[email protected]> wrote:
> >
> > > On Thu, Sep 21, 2023 at 04:54:00AM +0000, Justin Stitt wrote:
> > > > `strncpy` is deprecated for use on NUL-terminated destination strings [1].
> > > >
> > > > We should prefer more robust and less ambiguous string interfaces.
> > > >
> > > > We expect adc->chan_name[val] to be NUL-terminated based on ch_name's
> > > > use within functions that expect NUL-terminated strings like strncmp and
> > > > printf-likes:
> > > > | if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) {
> > > > | /* Check internal channel availability */
> > > > | switch (i) {
> > > > | case STM32_ADC_INT_CH_VDDCORE:
> > > > | if (!adc->cfg->regs->or_vddcore.reg)
> > > > | dev_warn(&indio_dev->dev,
> > > > | "%s channel not available\n", ch_name);
> > > > ...
> > > >
> > > > There is no evidence that NUL-padding is needed either.
> > >
> > > Agreed -- it's used as a C string everywhere I can see.
> > >
> > > >
> > > > 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. If, for any reason, NUL-padding _is_
> > > > required we should go for `strscpy_pad`.
> > > >
> > > > 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: [email protected]
> > > > Signed-off-by: Justin Stitt <[email protected]>
> > > > ---
> > > > Note: build-tested
> > > > ---
> > > > drivers/iio/adc/stm32-adc.c | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> > > > index f7613efb870d..9cdcf396d901 100644
> > > > --- a/drivers/iio/adc/stm32-adc.c
> > > > +++ b/drivers/iio/adc/stm32-adc.c
> > > > @@ -2209,7 +2209,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev,
> > > > ret = -EINVAL;
> > > > goto err;
> > > > }
> > > > - strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
> > > > + strscpy(adc->chan_name[val], name, STM32_ADC_CH_SZ);
> > >
> > > I still prefer sizeof($dst), but yes, these are the same:
> > >
> > > char chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
> > >
> > > If this needs a v2, please improve the Subject, but it is technically
> > > correct, so:
> >
> > Hi Kees,
> >
> > I can tweak the subject whilst applying. What did you have in mind
> > as a better one?
>
> I would use "iio: adc: stm32-adc: Replace deprecated strncpy() with strscpy()"
Makes sense. I also used the () approach to identify functions in the
text of the patch description instead of `funcname`
Applied with those tweaks to the togreg branch of iio.git but initially
just pushed out as testing to let 0-day take a look at it.
Thanks,
Jonathan
>
> Thanks!
>
> -Kees
>