Re: [PATCH linux-next] accessibility: speakup: use strscpy() to instead of strncpy()

[Samuel Thibault]

yang.yang29@xxxxxxxxxx, le sam. 03 déc. 2022 14:21:28 +0800, a ecrit:
> From: Xu Panda <xu.panda@xxxxxxxxxx>
> 
> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL terminated strings.
> 
> Signed-off-by: Xu Panda <xu.panda@xxxxxxxxxx>
> Signed-off-by: Yang Yang <yang.yang29@xxxxxxx>
> ---
>  drivers/accessibility/speakup/kobjects.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/accessibility/speakup/kobjects.c b/drivers/accessibility/speakup/kobjects.c
> index a7522d409802..273c076b661a 100644
> --- a/drivers/accessibility/speakup/kobjects.c
> +++ b/drivers/accessibility/speakup/kobjects.c
> @@ -426,8 +426,7 @@ static ssize_t synth_direct_store(struct kobject *kobj,
>  	spin_lock_irqsave(&speakup_info.spinlock, flags);
>  	while (len > 0) {
>  		bytes = min_t(size_t, len, 250);
> -		strncpy(tmp, ptr, bytes);
> -		tmp[bytes] = '\0';
> +		strscpy(tmp, ptr, bytes);

This needs to be bytes+1, otherwise the trailing `\0` will be put at
bytes-1 instead of bytes as the original code does, thus eating one
character.

>  		string_unescape_any_inplace(tmp);
>  		synth_printf("%s", tmp);
>  		ptr += bytes;
> -- 
> 2.15.2
>