From: Pavel Emelyanov <xemul@openvz.org>
To: David Miller <davem@davemloft.net>
Cc: Linux Netdev List <netdev@vger.kernel.org>, devel@openvz.org
Subject: [PATCH 0/4] Fix race between sk_filter reassign and sk_clone()
Date: Wed, 17 Oct 2007 13:45:54 +0400 [thread overview]
Message-ID: <4715D9D2.8070102@openvz.org> (raw)
The race can result in that some sock will get an sk_filter
pointer set to kfree-d memory. Look
CPU1: CPU2:
sk_clone(): sk_attach_filter():
new_sk = sk_alloc(...);
sock_copy(new_sk, sk);
/* copies the filter ptr */
...
filter = new_sk->sk_filter;
if (filter)
old_fp = sk->sk_filter;
...
sk_filter_release(old_fp);
if (atomic_dec_and_test(&old_fp->refcnt))
atomic_inc(&filter->refcnt);
/* true */
call_rcu(&fp->rcu, kfree);
that's it - after a quiescent state pass the new_sk will have
a pointer on kfree-d filter.
The same problem exists for detaching filter (SO_DETACH_FILTER).
The proposed fix consists of 3 preparation patches and the fix itself.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
next reply other threads:[~2007-10-17 9:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-17 9:45 Pavel Emelyanov [this message]
2007-10-17 9:47 ` [PATCH 1/4] Introduce the sk_detach_filter() call Pavel Emelyanov
2007-10-17 9:49 ` [PATCH 2/4] Move the filter releasing into a separate call Pavel Emelyanov
2007-10-17 9:51 ` [PATCH 3/4] Cleanup the error path in sk_attach_filter Pavel Emelyanov
2007-10-17 9:53 ` [PATCH 4/4] Fix the race between sk_filter_(de|at)tach and sk_clone() Pavel Emelyanov
2007-10-18 4:23 ` [PATCH 0/4] Fix race between sk_filter reassign " David Miller
2007-10-19 2:29 ` Olof Johansson
2007-10-19 4:55 ` David Miller
2007-10-19 7:37 ` Pavel Emelyanov
2007-10-19 7:52 ` David Miller
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