Messages in this thread | | | From | "Eric W. Biederman" <> | Date | Wed, 27 Apr 2022 11:33:40 -0500 | Subject | Re: [PATCH 9/9] ptrace: Don't change __state |
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Oleg Nesterov <oleg@redhat.com> writes:
> On 04/26, Eric W. Biederman wrote: >> >> @@ -253,7 +252,7 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state) >> */ >> if (lock_task_sighand(child, &flags)) { >> if (child->ptrace && child->parent == current) { >> - WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED); >> + WARN_ON(child->jobctl & JOBCTL_DELAY_WAKEKILL); > > This WARN_ON() doesn't look right. > > It is possible that this child was traced by another task and PTRACE_DETACH'ed, > but it didn't clear DELAY_WAKEKILL.
That would be a bug. That would mean that PTRACE_DETACHED process can not be SIGKILL'd.
> If the new debugger attaches and calls ptrace() before the child takes siglock > ptrace_freeze_traced() will fail, but we can hit this WARN_ON().
Eric
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