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SubjectRe: [ 020/184] ptrace: ensure arch_ptrace/ptrace_request can never
On 06/05, Oleg Nesterov wrote:
>
> On 06/05, Luis Henriques wrote:
> >
> > /* Ensure that nothing can wake it up, even SIGKILL */
> > -static bool ptrace_freeze_traced(struct task_struct *task)
> > +static bool ptrace_freeze_traced(struct task_struct *task, int kill)
> > {
> > - bool ret = false;
> > + bool ret = true;
> >
> > spin_lock_irq(&task->sighand->siglock);
> > - if (task_is_traced(task) && !__fatal_signal_pending(task)) {
> > + if (task_is_stopped(task) && !__fatal_signal_pending(task))
> > task->state = __TASK_TRACED;
> > - ret = true;
> > + else if (!kill) {
> > + if (task_is_traced(task) && !__fatal_signal_pending(task))
> > + task->state = __TASK_TRACED;
> > + else
> > + ret = false;
> > }
> > spin_unlock_irq(&task->sighand->siglock);
> >
> > @@ -131,7 +135,7 @@ int ptrace_check_attach(struct task_struct *child, int kill)
> > * child->sighand can't be NULL, release_task()
> > * does ptrace_unlink() before __exit_signal().
> > */
> > - if (kill || ptrace_freeze_traced(child))
> > + if (ptrace_freeze_traced(child, kill))
> > ret = 0;
>
> I can't apply this patch, probably I misread it...
>
> But it looks very wrong. It seems that ptrace_freeze_traced(kill => true)
> always succeeds? Even if task is TASK_RUNNING/UNINTERRUPTIBLE/etc ?

I am sorry for noise!

Yes I misread the patch. Now I actually applied both patches and
I believe the fix is fine.

ptrace_freeze_traced(kill => true) succeeds, but this is correct.
Somehow I confused this case with !kill.

Oleg.



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