Re: [PATCH 01/28] ALSA: ac97: Refactor snd_ac97_get_name() to use snprintf()

[David Laight <david.laight.linux@gmail.com>]

On Tue, 15 Sep 2026 11:39:34 -0700
Kees Cook <kees@kernel.org> wrote:

(I've just juked a lot of the 'reply to' list - too long to gmail.)

> On Tue, Sep 15, 2026 at 08:18:18AM +0000, Bill Wendling wrote:
> > --- a/sound/pci/ac97/ac97_codec.c
> > +++ b/sound/pci/ac97/ac97_codec.c
> > @@ -1850,10 +1850,12 @@ void snd_ac97_get_name(struct snd_ac97 *ac97, unsigned int id, char *name,
> >  
> >  	pid = look_for_codec_id(snd_ac97_codec_ids, id);
> >  	if (pid) {
> > -		strlcat(name, " ", maxlen);
> > -		strlcat(name, pid->name, maxlen);
> > +		int l = strlen(name);
> > +
> >  		if (pid->mask != 0xffffffff)
> > -			sprintf(name + strlen(name), " rev %u", id & ~pid->mask);
> > +			snprintf(name + l, maxlen - l, " %s rev %u", pid->name, id & ~pid->mask);
> > +		else
> > +			snprintf(name + l, maxlen - l, " %s", pid->name);
> >  		if (ac97 && pid->patch) {
> >  			if ((modem && (pid->flags & AC97_MODEM_PATCH)) ||
> >  			    (! modem && ! (pid->flags & AC97_MODEM_PATCH)))
> > @@ -1861,6 +1863,7 @@ void snd_ac97_get_name(struct snd_ac97 *ac97, unsigned int id, char *name,
> >  		}
> >  	} else {
> >  		int l = strlen(name);
> > +
> >  		snprintf(name + l, maxlen - l, " id %x", id & 0xff);
> >  	}
> >  }  
> 
> I'd rather not open-code the length math here. Can't we use seq_buf()
> instead?
> 

Or just use the length returned by the strscpy() call that wrote the initial
part of name[].
The return the name length so the callers don't have to use strcat()
themselves.
Replacing strlcat() with strlen() and a copy is just pointless.

David