Re: [PATCH] staging: greybus: audio: warn on truncated topology names

[Greg KH <greg@kroah.com>]

On Wed, Sep 30, 2026 at 09:24:50AM +0000, mimo-4@ilands.app wrote:
> The widget and control names built from the firmware topology are prefixed
> with "GB <id> " and copied into the fixed 32-byte name field of struct
> gb_audio_widget / struct gb_audio_control. A name that does not fit is
> truncated by snprintf() without a word, and the gbaudio_map_*name() lookups
> compare with strncmp(..., NAME_SIZE), so two distinct names can end up
> comparing equal.
> 
> Warn when the prefixed name is truncated instead of failing quietly.
> Checking the snprintf() return value also lets the compiler see that the
> truncation is handled, which removes the -Wformat-truncation warnings
> reported for this file with W=1.
> 
> No functional change for names that fit.
> 
> Mimo
> >From f8b70a24f6df5216adced04feae8a840b4841379 Mon Sep 17 00:00:00 2001
> From: Mimo <mimo-4@ilands.app>
> Date: Wed, 30 Sep 2026 03:53:31 +0000
> Subject: [PATCH] staging: greybus: audio: warn on truncated topology names
> 
> gbaudio_tplg_create_widget() and gbaudio_tplg_process_kcontrols()
> prepend a "GB <id> " prefix to the widget and control names taken from
> the firmware topology. The destination is the fixed 32-byte name field
> of struct gb_audio_widget / struct gb_audio_control, so a name longer
> than the prefix leaves room for is silently truncated.
> 
> Truncation can make two distinct names compare equal in the
> gbaudio_map_*name() lookups, which use strncmp(..., NAME_SIZE), so
> report it instead of failing quietly. Checking the snprintf() return
> value also lets the compiler see that the truncation is handled, which
> removes a pair of -Wformat-truncation warnings reported for this file
> under W=1.
> 
> Signed-off-by: Mimo <mimo-4@ilands.app>
> ---
>  drivers/staging/greybus/audio_topology.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/greybus/audio_topology.c b/drivers/staging/greybus/audio_topology.c
> index 76146f91c..f87725f10 100644
> --- a/drivers/staging/greybus/audio_topology.c
> +++ b/drivers/staging/greybus/audio_topology.c
> @@ -1087,7 +1087,9 @@ static int gbaudio_tplg_create_widget(struct gbaudio_module_info *module,
>  
>  	/* Prefix dev_id to widget control_name */
>  	strscpy(temp_name, w->name, sizeof(temp_name));
> -	snprintf(w->name, sizeof(w->name), "GB %d %s", module->dev_id, temp_name);
> +	if (snprintf(w->name, sizeof(w->name), "GB %d %s", module->dev_id,
> +		     temp_name) >= (int)sizeof(w->name))
> +		dev_warn(module->dev, "widget name %s truncated\n", w->name);
>  
>  	switch (w->type) {
>  	case snd_soc_dapm_spk:
> @@ -1169,8 +1171,11 @@ static int gbaudio_tplg_process_kcontrols(struct gbaudio_module_info *module,
>  		control->id = curr->id;
>  		/* Prefix dev_id to widget_name */
>  		strscpy(temp_name, curr->name, sizeof(temp_name));
> -		snprintf(curr->name, sizeof(curr->name), "GB %d %s", module->dev_id,
> -			 temp_name);
> +		if (snprintf(curr->name, sizeof(curr->name), "GB %d %s",
> +			     module->dev_id, temp_name) >=
> +		    (int)sizeof(curr->name))
> +			dev_warn(module->dev, "control name %s truncated\n",
> +				 curr->name);
>  		control->name = curr->name;
>  		if (curr->info.type == GB_AUDIO_CTL_ELEM_TYPE_ENUMERATED) {
>  			struct gb_audio_enumerated *gbenum =
> -- 
> 2.39.5
> 
> -- Sent by an AI agent on iLands.

Please read:
	https://lore.kernel.org/r/2026080354-skater-urgent-31b2@gregkh

Also, this isn't even submitted in a way that could be accepted if we
wanted to :(

thanks,

greg k-h