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From: Arnd Bergmann <arnd@arndb.de>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, 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 15:50:10 +0100
Message-ID: <201103211550.10694.arnd@arndb.de> (raw)
In-Reply-To: <1300714346.2884.284.camel@edumazet-laptop>

On Monday 21 March 2011, Eric Dumazet wrote:
> [PATCH] ipx: fix ipx_release()
> 
> Commit b0d0d915d1d1a0 (remove the BKL) added a regression, because
> sock_put() can free memory while we are going to use it later.
> 
> Fix is to delay sock_put() after release_sock().
> 
> Reported-by: Ingo Molnar <mingo@elte.hu>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> Cc: Arnd Bergmann <arnd@arndb.de>

Your fix looks good, thanks Eric!

Acked-by: Arnd Bergmann <arnd@arndb.de>

I believe I made the same mistake in atalk_release and x25_release:

8<------------
net: fix atalk_release and x25_release

The recent BKL removal has introduced a use-after-free problem
in multiple network protocols. This fixes the problem in appletalk
and x25 by ensuring that we call the final sock_put() after
releasing the socket lock.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
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;
 }
 
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;
 }
 

  reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-21  2:51 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 [this message]
2011-03-21 14:55       ` Eric Dumazet
2011-03-21 15:22         ` Arnd Bergmann
2011-03-21 16:16           ` Ingo Molnar
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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