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Message-ID: <20120314185538.GB14172@redhat.com>
Date: Wed, 14 Mar 2012 19:55:38 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Djalal Harouni <tixxdz@...ndz.org>, Alan Cox <alan@...rguk.ukuu.org.uk>,
linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
Al Viro <viro@...iv.linux.org.uk>,
Alexey Dobriyan <adobriyan@...il.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Vasiliy Kulikov <segoon@...nwall.com>,
Kees Cook <keescook@...omium.org>, Solar Designer <solar@...nwall.com>,
WANG Cong <xiyou.wangcong@...il.com>,
James Morris <james.l.morris@...cle.com>,
linux-security-module@...r.kernel.org, linux-fsdevel@...r.kernel.org,
Greg KH <gregkh@...uxfoundation.org>, Ingo Molnar <mingo@...e.hu>,
Stephen Wilson <wilsons@...rt.ca>,
"Jason A. Donenfeld" <Jason@...c4.com>,
Roland McGrath <roland@...k.frob.com>
Subject: [PATCH 1/1] CLONE_PARENT shouldn't allow to set ->exit_signal
The child must not control its ->exit_signal, it is the parent who
decides which signal the child should use for notification.
This means that CLONE_PARENT should not use "clone_flags & CSIGNAL",
the forking task is the sibling of the new process and their parent
doesn't control exit_signal in this case.
This patch uses ->exit_signal of the forking process, but perhaps
we should simply use SIGCHLD.
We read group_leader->exit_signal lockless, this can race with the
ORIGINAL_SIGNAL -> SIGCHLD transition, but this is fine.
Potentially this change allows to kill self_exec_id/parent_exec_id.
Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
kernel/fork.c | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/kernel/fork.c b/kernel/fork.c
index b77fd55..34d7ed1 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1310,7 +1310,13 @@ static struct task_struct *copy_process(unsigned long clone_flags,
clear_all_latency_tracing(p);
/* ok, now we should be set up.. */
- p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
+ if (clone_flags & CLONE_THREAD)
+ p->exit_signal = -1;
+ else if (clone_flags & CLONE_PARENT)
+ p->exit_signal = current->group_leader->exit_signal;
+ else
+ p->exit_signal = (clone_flags & CSIGNAL);
+
p->pdeath_signal = 0;
p->exit_state = 0;
--
1.5.5.1
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