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; -- 18.104.22.168
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