linux-kernel - Re: [PATCH 2/5] sched,ptrace: Fix ptrace_check_attach() vs PREEMPT

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]

Message-ID: <20220415105755.GA15217@redhat.com>
Date:   Fri, 15 Apr 2022 12:57:56 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     rjw@...ysocki.net, mingo@...nel.org, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, mgorman@...e.de,
        ebiederm@...ssion.com, bigeasy@...utronix.de,
        Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org,
        tj@...nel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH 2/5] sched,ptrace: Fix ptrace_check_attach() vs PREEMPT_RT

On 04/15, Oleg Nesterov wrote:
>
> OK, so far it seems that this patch needs a couple of simple fixes you
> pointed out, but before I send V2:
>
> 	- do you agree we can avoid JOBCTL_TRACED_FROZEN in 1-2 ?
>
> 	- will you agree if I change ptrace_freeze_traced() to rely
> 	  on __state == TASK_TRACED rather than task_is_traced() ?
>

Forgot to say, I think 1/5 needs some changes in any case...

ptrace_resume() does  wake_up_state(child, __TASK_TRACED) but doesn't
clear JOBCTL_TRACED. The "else" branch in ptrace_stop() leaks this flag
too. Perhaps I missed something, I'll reread 1/5 again, but the main
question to me is whether 1-2 actually need the JOBCTL_TRACED_FROZEN flag.

Oleg.