Re: [PATCH] Input: mouse: vsxxxaa: Replace strlcat() with strscpy()

[Alejandro Colomar <alx+linux-hardening@kernel.org>]

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Hi Kees, Mariia,

> Date: 2026-11-12 10:27:58-0800
> From: Kees Cook <kees@kernel.org>
>
> On Thu, Nov 05, 2026 at 11:28:13AM +0000, David Laight wrote:
> > On Tue,  3 Nov 2026 22:23:18 -0800
> > Mariia Nikitash <nikitash.mariiaw@gmail.com> wrote:
> > 
> > > In preparation for removing the deprecated strlcat() API[1], use
> > > strscpy() to initialize the mouse device name.
> > > 
> > > The destination is zero-initialized, and the constant string fits
> > > within the buffer. Since the return value is unused, this preserves
> > > the existing behavior.
> > > 
> > > Link: https://github.com/KSPP/linux/issues/370 [1]
> > > Signed-off-by: Mariia Nikitash <nikitash.mariiaw@gmail.com>
> > > ---
> > >  drivers/input/mouse/vsxxxaa.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/input/mouse/vsxxxaa.c b/drivers/input/mouse/vsxxxaa.c
> > > index 042a17fe81db..b3a0d7ff5738 100644
> > > --- a/drivers/input/mouse/vsxxxaa.c
> > > +++ b/drivers/input/mouse/vsxxxaa.c
> > > @@ -463,8 +463,8 @@ static int vsxxxaa_connect(struct serio *serio, struct serio_driver *drv)
> > >  
> > >  	mouse->dev = input_dev;
> > >  	mouse->serio = serio;
> > > -	strlcat(mouse->name, "DEC VSXXX-AA/-GA mouse or VSXXX-AB digitizer",
> > > -		 sizeof(mouse->name));
> > > +	strscpy(mouse->name, "DEC VSXXX-AA/-GA mouse or VSXXX-AB digitizer",
> > > +		sizeof(mouse->name));
> > 
> > You might as well use the 2 argument form.
> 
> I'd agree: this is a true array, so the sizeof() can be dropped. But
> it's also exactly the same binary output, so I'm fine either way:

Indeed, the 2-arg strscpy() call would be much safer.  I'd prefer using
it, since we can.


Have a lovely night!
Alex

> 
> Reviewed-by: Kees Cook <kees@kernel.org>
> 
> And I echo the surprise over strlcat being used on an empty string. :P
> 
> -- 
> Kees Cook
> 

-- 
<https://www.alejandro-colomar.es>

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