Oleg Nesterov <oleg@xxxxxxxxxx> writes:
> 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.
Great, thanks a lot for clarifying this, Oleg.
Cheers,
--
Luis
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