From: Oleg Nesterov <oleg@redhat.com>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: PATCH? process_32.c:__switch_to() calls __math_state_restore() before updating current_task
Date: Sat, 6 Feb 2010 13:06:40 +0100 [thread overview]
Message-ID: <20100206120640.GA22280@redhat.com> (raw)
In-Reply-To: <20100205124407.GA24974@redhat.com>
On 02/05, Oleg Nesterov wrote:
>
> In short: why restore_i387_xstate() does init_fpu() when !used_math(),
> can't (or shouldn't) it merely do set_used_math() ?
>
> restore_i387_xstate:
>
> if (!used_math()) {
> err = init_fpu(tsk);
> if (err)
> return err;
> }
>
> note that buf != NULL. This means that used_math() was true when
> get_sigframe() was called, otherwise buf == sigcontext->fpstate
> would be NULL, right?
>
> So, the task must have the valid ->thread.xstate,
This is probably correct. But a malicious user can set sc->fpsate
and fool the kernel, so we must assume buf != NULL implies the
valid ->xstate.
Oleg.
next prev parent reply other threads:[~2010-02-06 12:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-04 16:51 PATCH? process_32.c:__switch_to() calls __math_state_restore() before updating current_task Oleg Nesterov
2010-02-04 17:40 ` Suresh Siddha
2010-02-05 12:44 ` Oleg Nesterov
2010-02-06 12:06 ` Oleg Nesterov [this message]
2010-02-06 12:08 ` Oleg Nesterov
2010-02-08 18:48 ` Suresh Siddha
2010-02-08 20:26 ` Oleg Nesterov
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