linux-kernel - [PATCH 2/2] ptrace: task_stopped_code(ptrace => true) can't see TASK

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Message-ID: <20151119184752.GC19061@redhat.com>
Date:	Thu, 19 Nov 2015 19:47:52 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:	Roland McGrath <roland@...k.frob.com>, Tejun Heo <tj@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Pedro Alves <palves@...hat.com>,
	Jan Kratochvil <jan.kratochvil@...hat.com>
Subject: [PATCH 2/2] ptrace: task_stopped_code(ptrace => true) can't see
	TASK_STOPPED task

task_stopped_code()->task_is_stopped_or_traced() doesn't look right,
the traced task must never be TASK_STOPPED.

We can not add WARN_ON(task_is_stopped(p)), but this is only because
do_wait() can race with PTRACE_ATTACH from another thread.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/exit.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index c090738..fc7b4ec 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1127,7 +1127,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 static int *task_stopped_code(struct task_struct *p, bool ptrace)
 {
 	if (ptrace) {
-		if (task_is_stopped_or_traced(p) &&
+		if (task_is_traced(p) &&
 		    !(p->jobctl & JOBCTL_LISTENING))
 			return &p->exit_code;
 	} else {
-- 
1.5.5.1


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