From: Peter Zijlstra <peterz@infradead.org>
To: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Corey Hickey <bugfood-ml@fatooh.org>,
linux-kernel@vger.kernel.org,
Bharata B Rao <bharata@linux.vnet.ibm.com>,
Balbir Singh <balbir@in.ibm.com>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Ingo Molnar <mingo@elte.hu>,
mtk.manpages@gmail.com
Subject: Re: RT scheduling and a way to make a process hang, unkillable
Date: Mon, 16 Feb 2009 15:23:24 +0100 [thread overview]
Message-ID: <1234794204.30178.10.camel@laptop> (raw)
In-Reply-To: <1234790371.30178.8.camel@laptop>
On Mon, 2009-02-16 at 14:19 +0100, Peter Zijlstra wrote:
> On Mon, 2009-02-16 at 18:44 +0530, Dhaval Giani wrote:
> > (This is not a good day!)
>
> Monday strikes again ;-)
>
> > @@ -572,6 +572,9 @@ static int set_user(struct cred *new)
> > if (!new_user)
> > return -EAGAIN;
>
> So here we just allocated new_user and made sure we didn't fail that
> allocation.
>
> > + if (!task_can_switch_user(new->uid, current))
> > + return -EAGAIN;
>
> And here you bail, without freeing new_user. The idea was to do this
> check before alloc_uid().
>
> > if (atomic_read(&new_user->processes) >=
> > current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
> > new_user != INIT_USER) {
Ah, I now see I send you down a hole here,.. your find_user() in
task_can_switch_user() relies on that alloc_uid(). So you have to do it
after, and just free the new_user thingy when the test fails.
next prev parent reply other threads:[~2009-02-16 14:23 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-15 0:51 RT scheduling and a way to make a process hang, unkillable Corey Hickey
2009-02-15 11:24 ` Peter Zijlstra
2009-02-16 10:36 ` Dhaval Giani
2009-02-16 11:08 ` Peter Zijlstra
2009-02-16 12:02 ` Dhaval Giani
2009-02-16 12:24 ` Peter Zijlstra
2009-02-16 13:14 ` Dhaval Giani
2009-02-16 13:19 ` Peter Zijlstra
2009-02-16 14:23 ` Peter Zijlstra [this message]
2009-02-16 13:20 ` Dhaval Giani
2009-02-16 19:18 ` Corey Hickey
2009-02-17 5:00 ` Dhaval Giani
2009-02-17 10:15 ` Dhaval Giani
2009-02-17 11:15 ` Peter Zijlstra
2009-02-18 0:09 ` Corey Hickey
2009-02-23 11:45 ` Dhaval Giani
2009-02-23 11:59 ` Peter Zijlstra
2009-02-24 9:18 ` Dhaval Giani
2009-02-24 15:58 ` Andi Kleen
2009-02-24 16:36 ` Peter Zijlstra
2009-02-24 19:29 ` Chris Friesen
2009-02-27 9:43 ` [PATCH] sched: Don't allow setuid to succeed if the user does not have rt bandwidth Dhaval Giani
2009-02-27 10:25 ` Ingo Molnar
2009-02-16 20:16 ` RT scheduling and a way to make a process hang, unkillable Kyle Moffett
2009-02-16 20:28 ` Peter Zijlstra
2009-02-17 7:22 ` Dhaval Giani
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