linux-kernel - Re: Race in ptrace.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Thu, 11 Feb 2010 13:05:48 -0800
From:	Salman Qazi <sqazi@...gle.com>
To:	Roland McGrath <roland@...hat.com>
Cc:	Oleg Nesterov <oleg@...hat.com>, taviso@...gle.com,
	Roland Dreier <rolandd@...co.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: Race in ptrace.

On Thu, Feb 11, 2010 at 12:55 PM, Roland McGrath <roland@...hat.com> wrote:
>> What I don't agree with is that when we send SIGCONT later with
>> "kill", we wake up the child at all.  It may make sense to someone who
>> has access to the kernel source code, but from a user's point of view
>> this is a surprise.  The signal is intercepted and should not have an
>> effect on the child.
>
> This is the behavior of SIGCONT and doesn't really have anything to do with
> ptrace.  Once you have let the SIGSTOP through, the process is in job
> control stop just like if you'd sent a SIGSTOP without using ptrace at all.
>
> The distinction that is confusing you is that *generating* SIGCONT is what
> resumes the process, not *delivering* it.  Another example is that if your
> process has SIGCONT blocked or ignored, SIGCONT still wakes it up.  Another
> example is that SIGCONT wakes up all the threads in a process, before one
> of those threads delivers the SIGCONT (i.e. runs a handler).

Thanks for the clarification.  This is exactly the bit of information
I was missing.

>
>
> Thanks,
> Roland
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/