| Date | Wed, 27 Apr 2022 18:09:03 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 9/9] ptrace: Don't change __state |
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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.
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().
Oleg.
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