linux-kernel - Re: timerfd: use-after-free in timerfd_remove

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Message-ID: <alpine.DEB.2.20.1701311244370.3457@nanos>
Date:   Tue, 31 Jan 2017 12:45:07 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Dmitry Vyukov <dvyukov@...gle.com>
cc:     Al Viro <viro@...iv.linux.org.uk>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: timerfd: use-after-free in timerfd_remove_cancel

On Tue, 31 Jan 2017, Thomas Gleixner wrote:

> On Mon, 30 Jan 2017, Dmitry Vyukov wrote:
> > 
> > Seems that ctx->might_cancel is racy.
> 
> Yes, it is. Fix below.

And the fix is racy as well. Darn, we really need to lock the context to
avoid that mess.