Re: [PATCH] ALSA: info: Use snprintf() in snd_info_card_create()

[Takashi Iwai <tiwai@suse.de>]

On Sat, 07 Nov 2026 14:57:09 +0100,
Thorsten Blum wrote:
> 
> On Sat, Nov 07, 2026 at 02:44:57PM +0100, Takashi Iwai wrote:
> > On Sat, 07 Nov 2026 14:04:33 +0100,
> > Thorsten Blum wrote:
> > > 
> > > On Sat, Nov 07, 2026 at 10:14:38AM +0100, Takashi Iwai wrote:
> > > > On Sat, 07 Nov 2026 01:43:37 +0100,
> > > > Thorsten Blum wrote:
> > > > > 
> > > > > While the current code works correctly, replace the unbounded sprintf()
> > > > > with snprintf() to bound the formatted string to the str buffer.
> > > > > 
> > > > > Signed-off-by: Thorsten Blum <blum@kernel.org>
> > > > 
> > > > Shouldn't we use scnprintf() instead?  Otherwise it may lead to a
> > > > compiler warning.
> > > 
> > > The only difference between snprintf() and scnprintf() is the return
> > > value, which is unused here. Both are correct and shouldn't trigger a
> > > warning.
> > 
> > Well, not really.  For this particular patch, it doesn't make
> > difference, but in some cases (like the use with %s), snprintf()
> > causes a spurious compile warning with W=1.  e.g. try below.
> 
> Agreed, although that's a different use case from my patch.
 
Yep.  I guess a warning is triggered only when filling a substring
that can be large into the fixed size buffer for now, but it's a
compiler's thing, that can change at any time in future...

> I don't see a warning when compiling my patch with W=1, but I'm happy to
> switch to scnprintf() if you prefer.

I'd like to bet for a safer way, so let's go with scnprintf().


thanks,

Takashi