linux-kernel - [PATCH 03/17] exit: Fix the exit_code for wait_task

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Date:   Mon,  3 Jan 2022 15:32:58 -0600
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-arch@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Al Viro <viro@...IV.linux.org.uk>,
        Kees Cook <keescook@...omium.org>, linux-api@...r.kernel.org,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 03/17] exit: Fix the exit_code for wait_task_zombie

The function wait_task_zombie is defined to always returns the process not
thread exit status.  Unfortunately when process group exit support
was added to wait_task_zombie the WNOWAIT case was overlooked.

Usually tsk->exit_code and tsk->signal->group_exit_code will be in sync
so fixing this is bug probably has no effect in practice.  But fix
it anyway so that people aren't scratching their heads about why
the two code paths are different.

History-Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Fixes: 2c66151cbc2c ("[PATCH] sys_exit() threading improvements, BK-curr")
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 kernel/exit.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index 34c43037450f..7121db37c411 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1011,7 +1011,8 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 		return 0;
 
 	if (unlikely(wo->wo_flags & WNOWAIT)) {
-		status = p->exit_code;
+		status = (p->signal->flags & SIGNAL_GROUP_EXIT)
+			? p->signal->group_exit_code : p->exit_code;
 		get_task_struct(p);
 		read_unlock(&tasklist_lock);
 		sched_annotate_sleep();
-- 
2.29.2