[PATCH linux-next v2] x86/platform/uv: use strscpy to instead of strncpy()

[PATCH linux-next v2] x86/platform/uv: use strscpy to instead of strncpy()

[yang.yang29]

From: Xu Panda <xu.panda@zte.com.cn>

The implementation of strscpy() is more robust and safer.
That's now the recommended way to copy NUL terminated strings.
---
change for v2
 - fix the mistake and make the code better and simpler,
thanks to Andy Shevchenko.
---

Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com>
Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 arch/x86/platform/uv/uv_nmi.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c
index a60af0230e27..d94140842aa3 100644
--- a/arch/x86/platform/uv/uv_nmi.c
+++ b/arch/x86/platform/uv/uv_nmi.c
@@ -205,11 +205,7 @@ static int param_set_action(const char *val, const struct kernel_param *kp)
 	char arg[ACTION_LEN], *p;

 	/* (remove possible '\n') */
-	strncpy(arg, val, ACTION_LEN - 1);
-	arg[ACTION_LEN - 1] = '\0';
-	p = strchr(arg, '\n');
-	if (p)
-		*p = '\0';
+	strscpy(arg, val, strnchrnul(val, ACTION_LEN, '\n') - val);

 	for (i = 0; i < n; i++)
 		if (!strcmp(arg, valid_acts[i].action))
-- 
2.15.2

Re: [PATCH linux-next v2] x86/platform/uv: use strscpy to instead of strncpy()

[Andy Shevchenko]

On Mon, Dec 5, 2022 at 1:42 PM <yang.yang29@zte.com.cn> wrote:
>
> From: Xu Panda <xu.panda@zte.com.cn>

Thank you for an update, my comments below.

> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL terminated strings.
> ---
> change for v2
>  - fix the mistake and make the code better and simpler,
> thanks to Andy Shevchenko.
> ---

This is (the changelog) in the wrong place.

> Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
> Signed-off-by: Yang Yang <yang.yang29@zte.com>

> Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>

No, I haven't given you this tag, sorry. The changelog is enough to give credit.

...

>         char arg[ACTION_LEN], *p;
>
>         /* (remove possible '\n') */
> -       strncpy(arg, val, ACTION_LEN - 1);
> -       arg[ACTION_LEN - 1] = '\0';
> -       p = strchr(arg, '\n');
> -       if (p)
> -               *p = '\0';
> +       strscpy(arg, val, strnchrnul(val, ACTION_LEN, '\n') - val);

And even better is to replace ACTION_LEN by sizeof(arg).

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH linux-next v2] x86/platform/uv: use strscpy to instead of strncpy()

[Andy Shevchenko]

On Mon, Dec 5, 2022 at 3:13 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Mon, Dec 5, 2022 at 1:42 PM <yang.yang29@zte.com.cn> wrote:

...

> >         char arg[ACTION_LEN], *p;
> >
> >         /* (remove possible '\n') */
> > -       strncpy(arg, val, ACTION_LEN - 1);
> > -       arg[ACTION_LEN - 1] = '\0';
> > -       p = strchr(arg, '\n');
> > -       if (p)
> > -               *p = '\0';
> > +       strscpy(arg, val, strnchrnul(val, ACTION_LEN, '\n') - val);
>
> And even better is to replace ACTION_LEN by sizeof(arg).

Btw, have you compiled this with `make W=1 ...`? I believe you will
get a new warning after your change.

-- 
With Best Regards,
Andy Shevchenko