On Fri, Jul 28, 2023 at 6:26 AM Justin Stitt <justinstitt@xxxxxxxxxx> wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings [1]. > > A suitable replacement is `strscpy` [2] due to the fact that it > guarantees NUL-termination on its destination buffer argument which is > _not_ always the case for `strncpy`! > > In this case, though, there was great care taken to ensure that the > destination buffer would be NUL-terminated through the use of `len - 1` > ensuring that the previously zero-initialized buffer would not overwrite > the last NUL byte. This means that there's no bug here. > > However, `strscpy` will add a mandatory NUL byte to the destination > buffer as promised by the following `strscpy` implementation [3]: > | /* Hit buffer length without finding a NUL; force NUL-termination. > */ > | if (res) > | dest[res-1] = '\0'; > > This means we can lose the `- 1` which clears up whats happening here. > All the while, we get one step closer to eliminating the ambiguous > `strncpy` api in favor of its less ambiguous replacement like `strscpy`, > `strscpy_pad`, `strtomem` and `strtomem_pad` amongst others. > > [1]: > www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings > [2]: manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html > [3]: https://elixir.bootlin.com/linux/v6.3/source/lib/string.c#L183 > > Link: https://github.com/KSPP/linux/issues/90 > Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx> > Acked-by: Shengjiu Wang <shengjiu.wang@xxxxxxxxx> Best regards wang shengjiu > --- > sound/soc/fsl/fsl_micfil.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/sound/soc/fsl/fsl_micfil.c b/sound/soc/fsl/fsl_micfil.c > index 3f08082a55be..fe28b27e50d0 100644 > --- a/sound/soc/fsl/fsl_micfil.c > +++ b/sound/soc/fsl/fsl_micfil.c > @@ -1044,7 +1044,7 @@ static int fsl_micfil_probe(struct platform_device > *pdev) > return -ENOMEM; > > micfil->pdev = pdev; > - strncpy(micfil->name, np->name, sizeof(micfil->name) - 1); > + strscpy(micfil->name, np->name, sizeof(micfil->name)); > > micfil->soc = of_device_get_match_data(&pdev->dev); > > > --- > base-commit: 57012c57536f8814dec92e74197ee96c3498d24e > change-id: 20230727-sound-soc-fsl-4fc5569d771e > > Best regards, > -- > Justin Stitt <justinstitt@xxxxxxxxxx> > >
