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Message-Id: <20220426225211.308418-7-ebiederm@xmission.com>
Date: Tue, 26 Apr 2022 17:52:09 -0500
From: "Eric W. Biederman" <ebiederm@...ssion.com>
To: linux-kernel@...r.kernel.org
Cc: rjw@...ysocki.net, Oleg Nesterov <oleg@...hat.com>,
mingo@...nel.org, vincent.guittot@...aro.org,
dietmar.eggemann@....com, rostedt@...dmis.org, mgorman@...e.de,
bigeasy@...utronix.de, Will Deacon <will@...nel.org>,
tj@...nel.org, linux-pm@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Richard Weinberger <richard@....at>,
Anton Ivanov <anton.ivanov@...bridgegreys.com>,
Johannes Berg <johannes@...solutions.net>,
linux-um@...ts.infradead.org, Chris Zankel <chris@...kel.net>,
Max Filippov <jcmvbkbc@...il.com>,
inux-xtensa@...ux-xtensa.org, Kees Cook <keescook@...omium.org>,
Jann Horn <jannh@...gle.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 7/9] ptrace: Simplify the wait_task_inactive call in ptrace_check_attach
Asking wait_task_inactive to verify that tsk->__state == __TASK_TRACED
was needed to detect the when ptrace_stop would decide not to stop
after calling "set_special_state(TASK_TRACED)". With the recent
cleanups ptrace_stop will always stop after calling set_special_state.
Take advatnage of this by no longer asking wait_task_inactive to
verify the state. If a bug is hit and wait_task_inactive does not
succeed warn and return -ESRCH.
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
kernel/ptrace.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 16d1a84a2cae..0634da7ac685 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -265,17 +265,9 @@ 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, 0)))
+ ret = -ESRCH;
return ret;
}
--
2.35.3
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