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SubjectRe: [patch] ptrace-fix-2.5.33-A1
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Ingo Molnar <mingo@elte.hu> writes:

> i've attached a combined patch of your two patches, against BK-curr. Looks
> good to me, and since it passed your more complex ptrace tests ...
>
> Ingo
>
> --- linux/kernel/exit.c.orig Fri Sep 6 00:55:02 2002
> +++ linux/kernel/exit.c Fri Sep 6 00:57:58 2002
> @@ -66,6 +66,11 @@
> atomic_dec(&p->user->processes);
> security_ops->task_free_security(p);
> free_uid(p->user);
> + if (unlikely(p->ptrace)) {
> + write_lock_irq(&tasklist_lock);
> + __ptrace_unlink(p);
> + write_unlock_irq(&tasklist_lock);
> + }
> BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));

Looks like it's need the only CLONE_DETACH process. Why it's here?

* Search them and reparent children.
*/
list_for_each(_p, &father->children) {
p = list_entry(_p,struct task_struct,sibling);
reparent_thread(p, reaper, child_reaper);
}

Looks like that tracer deprive a process from real parent.

list_for_each(_p, &father->ptrace_children) {
p = list_entry(_p,struct task_struct,ptrace_list);
reparent_thread(p, reaper, child_reaper);
}

Thread group makes the child which links both ->children and
->ptrace_children.

> {
> - ptrace_unlink(p);
> - list_del_init(&p->sibling);
> - p->ptrace = 0;
> + /* If we were tracing the thread, release it; otherwise preserve the
> + ptrace links. */
> + if (unlikely(traced)) {
> + task_t *trace_task = p->parent;
> + __ptrace_unlink(p);
> + p->ptrace = 1;

Unexpected change of ptrace flag.

> + __ptrace_link(p, trace_task);
> + } else {
> + p->ptrace = 0;
> + list_del_init(&p->sibling);
> + p->parent = p->real_parent;
> + list_add_tail(&p->sibling, &p->parent->children);

Looks like that tracing child still link ->ptrace_list.
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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