Message-ID: <1448483017.24696.33.camel@edumazet-glaptop2.roam.corp.google.com>
Subject: Re: use-after-free in sock_wake_async
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Rainer Weikusat <rweikusat@mobileactivedefense.com>
Cc: Eric Dumazet <edumazet@google.com>, Dmitry Vyukov <dvyukov@google.com>,
        Benjamin LaHaise <bcrl@kvack.org>,
        "David S. Miller" <davem@davemloft.net>,
        Hannes Frederic Sowa <hannes@stressinduktion.org>,
        Al Viro <viro@zeniv.linux.org.uk>, David Howells <dhowells@redhat.com>,
        Ying Xue <ying.xue@windriver.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        netdev <netdev@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        syzkaller <syzkaller@googlegroups.com>,
        Kostya Serebryany <kcc@google.com>,
        Alexander Potapenko <glider@google.com>,
        Sasha Levin <sasha.levin@oracle.com>
Date: Wed, 25 Nov 2015 12:23:37 -0800
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On Wed, 2015-11-25 at 11:50 -0800, Eric Dumazet wrote:

> >                 other->sk_data_ready(other);
> > +               unix_state_unlock(other);


Also, problem with such construct is that we wakeup a thread that will
block on the lock we hold.

Beauty of sk_data_ready() is to call it once we hold no lock any more,
to enable another cpu to immediately proceed.

In this case, 'other' can not disappear, so it should be safe.


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