Re: [PATCH] usb: gadget: f_uac1_legacy: fix inverted NULL check after kstrndup()

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jun 25, 2026 at 07:31:54PM +0800, Xu Yang wrote:
> From: Xu Yang <xu.yang_2@nxp.com>
> 
> kstrndup() returns NULL on allocation failure. The condition was
> checking 'if (tmp)' to detect failure, but this is inverted — it
> would treat a successful allocation as an error and return -ENOMEM
> while leaking the string, and proceed with a NULL pointer on failure.
> 
> Fix by changing the condition to 'if (!tmp)'.
> 
> Fixes: 0854611a19ae ("usb: gadget: f_uac1: add configfs support")
> Cc: stable@vger.kernel.org
> Assisted-by: Claude:claude-sonnet-4-6
> Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
> ---
>  drivers/usb/gadget/function/f_uac1_legacy.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/function/f_uac1_legacy.c b/drivers/usb/gadget/function/f_uac1_legacy.c
> index 5d201a2e30e7..e9f2632ce785 100644
> --- a/drivers/usb/gadget/function/f_uac1_legacy.c
> +++ b/drivers/usb/gadget/function/f_uac1_legacy.c
> @@ -914,7 +914,7 @@ static ssize_t f_uac1_opts_##name##_store(struct config_item *item,	\
>  		goto end;						\
>  									\
>  	tmp = kstrndup(page, len, GFP_KERNEL);				\
> -	if (tmp) {							\
> +	if (!tmp) {							\
>  		ret = -ENOMEM;						\
>  		goto end;						\
>  	}								\
> -- 
> 2.34.1
> 
> 

So this has never worked?  How has no one ever noticed that in the
decade this has been in the kernel?  Does that mean that no one uses
this file/driver and we can just remove it?

thanks,

greg k-h