linux-kernel - Re: [RFC,PATCH 14/14] utrace core

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

Date:	Mon, 14 Dec 2009 21:24:54 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Roland McGrath <roland@...hat.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Ananth Mavinakayanahalli <ananth@...ibm.com>,
	Christoph Hellwig <hch@...radead.org>,
	"Frank Ch. Eigler" <fche@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org, utrace-devel@...hat.com
Subject: Re: [RFC,PATCH 14/14] utrace core

On 12/14, Roland McGrath wrote:
>
> > > In the stopped cases, there are lots of locks and barriers and things
> > > after resuming.  (Oleg?)
> >
> > Every time the tracee resumes after TASK_TRACED it uses utrace->lock
> > to synchronize with utrace_control/etc, it must see any changes.
>
> And TASK_STOPPED?

SIGCONT can wake up the TASK_STOPPED tracee. I don't think the tracer
should ever rely on TASK_STOPPED (utrace never does). If the tracer
needs the "really stopped" tracee we have UTRACE_STOP, and this means
TASK_TRACED.

But I am not sure I understand this part of discussion... In any case
the tracee should see any changes which were done before the wakeup.
But TASK_STOPPED can't guarantee the tracee won't be resumed until
the tracer wakes it up. Of course, TASK_TRACED can't prevent SIGKILL,
but in this case we should only care about "the tracee can't resume
until we drop utrace->lock" case.

Oleg.

--
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/