On Sat, 23 Sep 2023 20:15:09 -0700
Kees Cook [off-list ref] wrote:
On Thu, Sep 21, 2023 at 04:54:00AM +0000, Justin Stitt wrote:
quoted
`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.
quoted
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: <redacted>
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
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 <redacted>
:)
-Kees
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