lkml.org 
[lkml]   [2022]   [May]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 08/11] ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs
On 05/04, Eric W. Biederman wrote:
>
> With the removal of the incomplete detection of the tracer going away
> in ptrace_stop, ptrace_stop always sleeps in schedule after
> ptrace_freeze_traced succeeds. Modify ptrace_check_attach to
> warn if wait_task_inactive fails.

Oh. Again, I don't understand the changelog. If we forget about RT,
ptrace_stop() will always sleep if ptrace_freeze_traced() succeeds.
may_ptrace_stop() has gone.

IOW. Lets forget about RT

> --- a/kernel/ptrace.c
> +++ b/kernel/ptrace.c
> @@ -266,17 +266,9 @@ static int ptrace_check_attach(struct task_struct *child, bool ignore_state)
> }
> read_unlock(&tasklist_lock);
>
> - if (!ret && !ignore_state) {
> - if (!wait_task_inactive(child, __TASK_TRACED)) {
> - /*
> - * This can only happen if may_ptrace_stop() fails and
> - * ptrace_stop() changes ->state back to TASK_RUNNING,
> - * so we should not worry about leaking __TASK_TRACED.
> - */
> - WARN_ON(READ_ONCE(child->__state) == __TASK_TRACED);
> - ret = -ESRCH;
> - }
> - }
> + if (!ret && !ignore_state &&
> + WARN_ON_ONCE(!wait_task_inactive(child, __TASK_TRACED)))
> + ret = -ESRCH;
>
> return ret;
> }

Why do you think this change would be wrong without any other changes?

Oleg.

\
 
 \ /
  Last update: 2022-05-05 17:03    [W:0.527 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site