linux-kernel - Re: [PATCH] ptrace: fix PTRACE_LISTEN race corrupting task->state

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Message-ID: <20170222170325.GB15968@redhat.com>
Date:   Wed, 22 Feb 2017 18:03:25 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     bsegall@...gle.com
Cc:     linux-kernel@...r.kernel.org, Roland McGrath <roland@...k.frob.com>
Subject: Re: [PATCH] ptrace: fix PTRACE_LISTEN race corrupting task->state

On 02/22, Oleg Nesterov wrote:
>
> note also that PTRACE_LISTEN itself can do ptrace_signal_wake_up(true),

please ignore, in this case the __TASK_TRACED at the start of _unfreeze()
saves us.

> 
> > This causes it to instead clobber TASK_WAKING,
> 
> even if it is already TASK_RUNNING it is simply wrong to set TASK_TRACED
> in both cases, right?
> 
> Thanks. The patch looks good at first glance, but let me think a bit...
> perhaps we should change PTRACE_LISTEN instead, not sure.
> 
> Oleg.