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From: Andrew Morton <akpm@linux-foundation.org>
To: bsegall@google.com
Cc: Oleg Nesterov <oleg@redhat.com>,
	linux-kernel@vger.kernel.org,
	Roland McGrath <roland@hack.frob.com>, Tejun Heo <tj@kernel.org>
Subject: Re: [PATCHv2] ptrace: fix PTRACE_LISTEN race corrupting task->state
Date: Tue, 4 Apr 2017 14:53:10 -0700	[thread overview]
Message-ID: <20170404145310.1de5e75f0bd916aef812e136@linux-foundation.org> (raw)
In-Reply-To: <xm26y3vfhmkp.fsf_-_@bsegall-linux.mtv.corp.google.com>

On Tue, 04 Apr 2017 14:47:34 -0700 bsegall@google.com wrote:

> In PT_SEIZED + LISTEN mode STOP/CONT signals cause a wakeup against
> __TASK_TRACED. If this races with the ptrace_unfreeze_traced at the end
> of a PTRACE_LISTEN, this can wake the task /after/ the check against
> __TASK_TRACED, but before the reset of state to TASK_TRACED. This causes
> it to instead clobber TASK_WAKING, allowing a subsequent wakeup against
> TRACED while the task is still on the rq wake_list, corrupting it.

The changelog doesn't convey the urgency of the fix.  To understand
this we'll need to know the user-visible impact of the bug and the
likelihood of someone hitting it.

Also your suggestion regarding which kernel version(s) should be fixed
(and the reasoning) is always valuable.

  reply	other threads:[~2017-04-04 21:53 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-21 18:47 [PATCH] ptrace: fix PTRACE_LISTEN race corrupting task->state bsegall
2017-02-22 16:55 ` Oleg Nesterov
2017-02-22 17:03   ` Oleg Nesterov
2017-02-22 17:56   ` bsegall
2017-02-24 16:36 ` Oleg Nesterov
2017-02-27 18:08   ` bsegall
2017-04-04 21:47   ` [PATCHv2] " bsegall
2017-04-04 21:53     ` Andrew Morton [this message]
2017-04-05 12:36       ` Oleg Nesterov
2017-04-05 12:30     ` Oleg Nesterov

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