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

[Takashi Iwai <tiwai@suse.de>]

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.


Takashi

--- a/sound/core/ump.c
+++ b/sound/core/ump.c
@@ -1369,7 +1369,7 @@ static void update_legacy_substreams(struct snd_ump_endpoint *ump,
 		name = ump->groups[idx].name;
 		if (!*name)
 			name = ump->core.name;
-		scnprintf(s->name, sizeof(s->name), "Group %d (%.16s)%s",
+		snprintf(s->name, sizeof(s->name), "Group %d (%.16s)%s",
 			  idx + 1, name,
 			  ump->groups[idx].active ? "" : " [Inactive]");
 		s->inactive = !ump->groups[idx].active;