Re: [alsa-devel] [PATCH] ALSA: xen: ensure nul-terminated device name

[Oleksandr Andrushchenko]

On 05/28/2018 06:59 PM, Arnd Bergmann wrote:
> gcc-8 warns that pcm_instance->name is not necessarily terminated correctly
> if the input is more than 80 characters long or lacks a termination byte
> itself:
>
> In function 'strncpy',
>      inlined from 'cfg_device' at sound/xen/xen_snd_front_cfg.c:399:3,
>      inlined from 'xen_snd_front_cfg_card' at sound/xen/xen_snd_front_cfg.c:509:9:
> include/linux/string.h:254:9: error: '__builtin_strncpy' specified bound 80 equals destination size [-Werror=stringop-truncation]
>    return __builtin_strncpy(p, q, size);
>
> Using strlcpy() instead of strncpy() makes this a bit safer.
>
> Fixes: fd3b36045c2c ("ALSA: xen-front: Read sound driver configuration from Xen store")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
>   sound/xen/xen_snd_front_cfg.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/sound/xen/xen_snd_front_cfg.c b/sound/xen/xen_snd_front_cfg.c
> index 38c7e1eefbb9..684b5f1d51ac 100644
> --- a/sound/xen/xen_snd_front_cfg.c
> +++ b/sound/xen/xen_snd_front_cfg.c
> @@ -396,7 +396,7 @@ static int cfg_device(struct xen_snd_front_info *front_info,
>   
>   	str = xenbus_read(XBT_NIL, device_path, XENSND_FIELD_DEVICE_NAME, NULL);
>   	if (!IS_ERR(str)) {
> -		strncpy(pcm_instance->name, str, sizeof(pcm_instance->name));
> +		strlcpy(pcm_instance->name, str, sizeof(pcm_instance->name));
>   		kfree(str);
>   	}
>   
Thank you for your patch,
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>