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From: Oleg Nesterov <oleg@redhat.com>
To: Salman Qazi <sqazi@google.com>
Cc: Roland Dreier <rolandd@cisco.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Roland McGrath <roland@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: Race in ptrace.
Date: Tue, 9 Feb 2010 12:27:00 +0100	[thread overview]
Message-ID: <20100209112700.GA4258@redhat.com> (raw)
In-Reply-To: <20100208143231.6d804590.akpm@linux-foundation.org>

Salman Qazi wrote:
>
> A race in ptrace was pointed to us by a fellow Google engineer, Tavis
> Ormandy.  The race involves interaction between a tracer, a tracee and
> an antagonist.  The tracer is tracing the tracee with PTRACE_SYSCALL and
> waits on the tracee.  In the mean time, an antagonist blasts the tracee
> with SIGCONTs.

Could you please explain how did observe this race? Do you have a
test-case, or could you explain how we can reproduce it?

Because,

> It turns out that a SIGCONT wakes up the
> tracee in kernel mode,

SIGCONT must not wake up a TASK_TRACED task.


Yes, there are some know problems with SIGCONT && ptrace, but I don't
see anthing related to the described problem.

Thanks,

Oleg.


  parent reply	other threads:[~2010-02-09 11:27 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-02-08 22:16 Race in ptrace Salman Qazi
     [not found] ` <20100208143231.6d804590.akpm@linux-foundation.org>
2010-02-09 11:27   ` Oleg Nesterov [this message]
2010-02-10 13:35     ` Oleg Nesterov
2010-02-10 18:38       ` Salman Qazi
2010-02-11 12:56         ` Oleg Nesterov
2010-02-11 16:32           ` Salman Qazi
2010-02-11 16:50             ` Oleg Nesterov
2010-02-11 18:43               ` Salman Qazi
2010-02-11 18:55                 ` Oleg Nesterov
2010-02-11 19:08                   ` Salman Qazi
2010-02-11 20:10                     ` Oleg Nesterov
2010-02-11 20:39                       ` Salman Qazi
2010-02-11 20:55                         ` Roland McGrath
2010-02-11 21:05                           ` Salman Qazi
2010-02-11 20:59                         ` Oleg Nesterov
  -- strict thread matches above, loose matches on Subject: below --
2010-02-08 22:04 Salman Qazi

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