linux-kernel - Re: [PATCH 5.10 09/38] llc: fix netdevice reference leaks in llc_ui

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Message-ID: <20220328090830.GA24435@amd>
Date:   Mon, 28 Mar 2022 11:08:30 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jakub Kicinski <kuba@...nel.org>, Pavel Machek <pavel@...x.de>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Eric Dumazet <edumazet@...gle.com>,
        赵子轩 <beraphin@...il.com>,
        Stoyan Manolov <smanolov@...e.de>
Subject: Re: [PATCH 5.10 09/38] llc: fix netdevice reference leaks in
 llc_ui_bind()

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.

Best regards,
								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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