From: Ingo Molnar <mingo@elte.hu>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
David Miller <davem@davemloft.net>,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [held lock freed] Re: [GIT] Networking
Date: Mon, 21 Mar 2011 17:16:27 +0100 [thread overview]
Message-ID: <20110321161627.GB28580@elte.hu> (raw)
In-Reply-To: <201103211622.40851.arnd@arndb.de>
* Arnd Bergmann <arnd@arndb.de> wrote:
> On Monday 21 March 2011, Eric Dumazet wrote:
> > > diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
> > > index 4680b1e..b2cf1db 100644
> > > --- a/net/x25/af_x25.c
> > > +++ b/net/x25/af_x25.c
> > > @@ -669,8 +669,8 @@ static int x25_release(struct socket *sock)
> > >
> > > sock_orphan(sk);
> > > out:
> > > - release_sock(sk);
> > > sock_put(sk);
> > > + release_sock(sk);
> > > return 0;
> > > }
> > >
> >
> > Hmm, x25_release() looks fine, I believe no fix is needed.
> >
>
> D'oh. You're right of course. My patch would introduce the bug,
> not fix it. Updated patch below.
>
> Arnd
> 8<-------------------------
> net/appletalk: fix atalk_release use after free
>
> The BKL removal in appletalk introduced a use-after-free problem,
> where atalk_destroy_socket frees a sock, but we still release
> the socket lock on it.
>
> An easy fix is to take an extra reference on the sock and sock_put
> it when returning from atalk_release.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> index 3d4f4b0..206e771 100644
> --- a/net/appletalk/ddp.c
> +++ b/net/appletalk/ddp.c
> @@ -1051,6 +1051,7 @@ static int atalk_release(struct socket *sock)
> {
> struct sock *sk = sock->sk;
>
> + sock_hold(sk);
> lock_sock(sk);
> if (sk) {
> sock_orphan(sk);
> @@ -1058,6 +1059,8 @@ static int atalk_release(struct socket *sock)
> atalk_destroy_socket(sk);
> }
> release_sock(sk);
> + sock_put(sk);
> +
> return 0;
> }
I have not triggered the lockdep warning in this code yet - but i've ran the
patch and have seen no ill effects from it so far.
Thanks,
Ingo
next prev parent reply other threads:[~2011-03-21 16:16 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-21 2:51 [GIT] Networking David Miller
2011-03-21 12:53 ` [held lock freed] " Ingo Molnar
2011-03-21 13:32 ` Eric Dumazet
2011-03-21 14:50 ` Arnd Bergmann
2011-03-21 14:55 ` Eric Dumazet
2011-03-21 15:22 ` Arnd Bergmann
2011-03-21 16:16 ` Ingo Molnar [this message]
2011-03-22 1:18 ` David Miller
2011-03-21 16:15 ` Ingo Molnar
2011-03-21 16:42 ` [slab poison overwritten] " Ingo Molnar
2011-03-21 17:37 ` Ingo Molnar
2011-03-21 17:39 ` Ingo Molnar
2011-03-21 18:07 ` Eric Dumazet
2011-03-21 20:15 ` Eric Dumazet
2011-03-21 22:13 ` Simon Horman
2011-03-21 23:29 ` Simon Horman
2011-03-22 0:01 ` Simon Horman
2011-03-22 0:17 ` Simon Horman
2011-03-22 1:18 ` Simon Horman
2011-03-22 3:40 ` David Miller
2011-03-22 3:39 ` David Miller
2011-03-22 9:56 ` Ingo Molnar
2011-03-22 10:00 ` Eric Dumazet
2011-03-22 21:52 ` Simon Horman
2011-03-22 9:07 ` Ingo Molnar
2011-03-22 1:16 ` [held lock freed] " David Miller
2011-03-21 19:24 ` Linus Torvalds
2011-03-21 20:10 ` Eric Dumazet
2011-03-22 4:09 ` David Miller
2011-03-22 10:00 ` Ingo Molnar
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