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__ptrace_detach: avoid task_detached(), check do_notify_parent()

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__ptrace_detach() relies on the current obscure behaviour of
do_notify_parent(tsk) which changes tsk->exit_signal if this child
should be silently reaped. That is why we check task_detached(), it
is true if the task is sub-thread, or it is the group_leader but
its exit_signal was changed by do_notify_parent().

This is confusing, change the code to rely on !thread_group_leader()
or the value returned by do_notify_parent().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Oleg Nesterov 2011-06-22 23:08:53 +02:00
parent 45cdf5cc07
commit 9843a1e977
1 changed files with 18 additions and 15 deletions
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33
kernel/ptrace.c
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@ -370,25 +370,28 @@ static int ignoring_children(struct sighand_struct *sigh)
*/ */
static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p) static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)
{ {
bool dead;
__ptrace_unlink(p); __ptrace_unlink(p);
if (p->exit_state == EXIT_ZOMBIE) { if (p->exit_state != EXIT_ZOMBIE)
if (!task_detached(p) && thread_group_empty(p)) { return false;
if (!same_thread_group(p->real_parent, tracer))
do_notify_parent(p, p->exit_signal); dead = !thread_group_leader(p);
else if (ignoring_children(tracer->sighand)) {
__wake_up_parent(p, tracer); if (!dead && thread_group_empty(p)) {
p->exit_signal = -1; if (!same_thread_group(p->real_parent, tracer))
} dead = do_notify_parent(p, p->exit_signal);
} else if (ignoring_children(tracer->sighand)) {
if (task_detached(p)) { __wake_up_parent(p, tracer);
/* Mark it as in the process of being reaped. */ p->exit_signal = -1;
p->exit_state = EXIT_DEAD; dead = true;
return true;
} }
} }
/* Mark it as in the process of being reaped. */
return false; if (dead)
p->exit_state = EXIT_DEAD;
return dead;
} }
static int ptrace_detach(struct task_struct *child, unsigned int data) static int ptrace_detach(struct task_struct *child, unsigned int data)