linux-kernel - Re: [PATCH] ptrace: fix clearing of JOBCTL_TRACED in ptrace_unfreeze

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Message-ID: <YsVuak0/upU2Rvm6@worktop.programming.kicks-ass.net>
Date:   Wed, 6 Jul 2022 13:13:46 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Sven Schnelle <svens@...ux.ibm.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ptrace: fix clearing of JOBCTL_TRACED in
 ptrace_unfreeze_traced()

On Wed, Jul 06, 2022 at 01:04:38PM +0200, Oleg Nesterov wrote:
> On 07/06, Sven Schnelle wrote:
> >
> > --- a/kernel/ptrace.c
> > +++ b/kernel/ptrace.c
> > @@ -222,7 +222,7 @@ static void ptrace_unfreeze_traced(struct task_struct *task)
> >  	if (lock_task_sighand(task, &flags)) {
> >  		task->jobctl &= ~JOBCTL_PTRACE_FROZEN;
> >  		if (__fatal_signal_pending(task)) {
> > -			task->jobctl &= ~TASK_TRACED;
> > +			task->jobctl &= ~JOBCTL_TRACED;
> 
> Heh. I have read this code many times, but I'm afraid I could read it
> 1000 times more and didn't notice the problem ;)

Heh, same here, I've read it today and didn't spot the problem. Brains
are weird.