Re: [PATCH 5.10 09/38] llc: fix netdevice reference leaks in llc_ui_bind()

Greg Kroah-Hartman
2022-03-28T09:13:07Z

On Mon, Mar 28, 2022 at 11:08:30AM +0200, Pavel Machek wrote:
> Hi!
>
> > > > Can someone check this? AFAICT this is buggy.
> > > >
> > > > static int llc_ui_autobind(struct socket *sock, struct sockaddr_llc *addr)
> > > > {
> > > > struct sock *sk = sock->sk;
> > > > struct llc_sock *llc = llc_sk(sk);
> > > > struct llc_sap *sap;
> > > > int rc = -EINVAL;
> > > >
> > > > if (!sock_flag(sk, SOCK_ZAPPED))
> > > > goto out;
> > > >
> > > > There are 'goto out's from both before dev_get() and after it,
> > > > dev_put() will be called with NULL pointer. dev_put() can't handle
> > > > NULL at least in the old kernels... this is simply confused.
> > > >
> > > > Mainline has dev_put_track() there, but I see same confusion.
> > > >
> > > > Best regards,
> > >
> > > commit 2d327a79ee17 ("llc: only change llc->dev when bind() succeeds"),
> > > https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=2d327a79ee176930dc72c131a970c891d367c1dc
> > >
> > > Should be in mainline on Thursday, LMK if we need to accelerate.
> > > IDK if anyone enables LLC2.
> >
> > I'll queue this up now, thanks.
>
> As the changelog says, this needs b37a46683739, otherwise there will
> be oops-es in even more cases.

If you look at the change, I think I already handled that issue. If
not, please let me know.

thanks,

greg k-h