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

[David Laight <david.laight.linux@gmail.com>]

On Wed, 8 Jul 2026 15:54:03 -0500
Frank Li <Frank.li@oss.nxp.com> wrote:

> On Wed, Jul 08, 2026 at 05:05:03PM +0200, Greg KH wrote:
> > 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?  
> 
> I think just no one use sys interface to change name.

Or doesn't notice/care that is didn't work and didn't try often
enough to leak enough memory to break things.

	David

> 
> Frank
> 
> >
> > thanks,
> >
> > greg k-h
> >  
>