From: Peter Zijlstra <peterz@infradead.org>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Dan Rosenberg <drosenberg@vsecurity.com>,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH] kptr_restrict for hiding kernel pointers from unprivileged users
Date: Fri, 10 Dec 2010 17:05:32 +0100 [thread overview]
Message-ID: <1291997132.13513.12.camel@laptop> (raw)
In-Reply-To: <1291865039.2795.46.camel@edumazet-laptop>
On Thu, 2010-12-09 at 04:23 +0100, Eric Dumazet wrote:
> > + if (kptr_restrict) {
> > + if (in_interrupt())
> > + WARN(1, "%%pK used in interrupt context.\n");
>
> So caller can not block BH ?
>
> This seems wrong to me, please consider :
>
> normal process context :
>
> spin_lock_bh() ...
>
> for (...)
> {xxx}printf( ... "%pK" ...)
>
> spin_unlock_bh();
That's a bug in in_interrupt(), one I've been pointing out for a long
while. Luckily we recently grew the infrastructure to deal with it.
If you write it as: if (in_irq() || in_serving_softirq() || in_nmi())
you'll not trigger for the above example.
Ideally in_serving_softirq() wouldn't exist and in_softirq() would do
what in_server_softirq() does -- which would make it symmetric with the
hardirq functions -- but nobody has found time to audit all in_softirq()
users.
prev parent reply other threads:[~2010-12-10 16:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1291863926.2965.1.camel@Dan>
2010-12-09 3:23 ` [PATCH] kptr_restrict for hiding kernel pointers from unprivileged users Eric Dumazet
2010-12-09 3:26 ` Eric Dumazet
2010-12-09 11:51 ` Dan Rosenberg
2010-12-09 12:46 ` Dan Rosenberg
2010-12-09 13:30 ` Eric Dumazet
2010-12-10 2:45 ` Dan Rosenberg
2010-12-10 16:05 ` Peter Zijlstra [this message]
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