[PATCH 05/16] ptrace: Remove dead code from __ptrace_detach

Eric W. Biederman
2022-05-18T22:53:44Z

Ever since commit 28d838cc4dfe ("Fix ptrace self-attach rule") it has
been impossible to attach another thread in the same thread group.

Remove the code from __ptrace_detach that was trying to support
detaching from a thread in the same thread group. The code is
dead and I can not make sense of what it is trying to do.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
kernel/ptrace.c | 24 +++---------------------
1 file changed, 3 insertions(+), 21 deletions(-)

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 328a34a99124..ca0e47691229 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -526,19 +526,6 @@ static int ptrace_traceme(void)
return ret;
}

-/*
- * Called with irqs disabled, returns true if childs should reap themselves.
- */
-static int ignoring_children(struct sighand_struct *sigh)
-{
- int ret;
- spin_lock(&sigh->siglock);
- ret = (sigh->action[SIGCHLD-1].sa.sa_handler = SIG_IGN) ||
- (sigh->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT);
- spin_unlock(&sigh->siglock);
- return ret;
-}
-
/*
* Called with tasklist_lock held for writing.
* Unlink a traced task, and clean it up if it was a traced zombie.
@@ -565,14 +552,9 @@ static bool __ptrace_detach(struct task_struct *tracer, struct task_struct *p)

dead = !thread_group_leader(p);

- if (!dead && thread_group_empty(p)) {
- if (!same_thread_group(p->real_parent, tracer))
- dead = do_notify_parent(p, p->exit_signal);
- else if (ignoring_children(tracer->sighand)) {
- __wake_up_parent(p, tracer);
- dead = true;
- }
- }
+ if (!dead && thread_group_empty(p))
+ dead = do_notify_parent(p, p->exit_signal);
+
/* Mark it as in the process of being reaped. */
if (dead)
p->exit_state = EXIT_DEAD;
--
2.35.3