From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8FD74C432C0 for ; Fri, 22 Nov 2019 10:32:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5EDF22071F for ; Fri, 22 Nov 2019 10:32:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574418744; bh=SFfvz0Kc7W4a0FIGmtaHxaA83yiAFH8FLxKr99BQamc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OtjAQgxPl8lH0uouKF/SZkVtVSQP6LnAgLbV/kykYhb0AxYfiE7NUF3hulYky5ylO qk4SELBkdpKmNm2uDtcAku4ZqPKniNg1EGUyjSaZ0IKri+udDXJXlTOy473p9mSbcJ HhFYjCY+6UUgGKLZGJWXOQRCD7qQO7E9YnCsnZFA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726822AbfKVKcX (ORCPT ); Fri, 22 Nov 2019 05:32:23 -0500 Received: from mail.kernel.org ([198.145.29.99]:53626 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727640AbfKVKcU (ORCPT ); Fri, 22 Nov 2019 05:32:20 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1BF102071B; Fri, 22 Nov 2019 10:32:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574418739; bh=SFfvz0Kc7W4a0FIGmtaHxaA83yiAFH8FLxKr99BQamc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i3MEFj2jAVMjEuHVwnelGL3TIjvJEgdEpfbkLYDOERZzzKbX+iQB8hRO6WbY5Y375 G4axvCuxg3r+tzHeJ/WDbwRN7RRRXcx3o4K7o/ngiDHBgPCnL3Vc8mXbF7bCjYo33D jhA3JHXRqkWOCDaVSROEZjhE30ILRD50w8AcC8XM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Gleixner , "Eric W. Biederman" , Sasha Levin Subject: [PATCH 4.4 036/159] signal: Always ignore SIGKILL and SIGSTOP sent to the global init Date: Fri, 22 Nov 2019 11:27:07 +0100 Message-Id: <20191122100731.907587368@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191122100704.194776704@linuxfoundation.org> References: <20191122100704.194776704@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric W. Biederman [ Upstream commit 86989c41b5ea08776c450cb759592532314a4ed6 ] If the first process started (aka /sbin/init) receives a SIGKILL it will panic the system if it is delivered. Making the system unusable and undebugable. It isn't much better if the first process started receives SIGSTOP. So always ignore SIGSTOP and SIGKILL sent to init. This is done in a separate clause in sig_task_ignored as force_sig_info can clear SIG_UNKILLABLE and this protection should work even then. Reviewed-by: Thomas Gleixner Signed-off-by: "Eric W. Biederman" Signed-off-by: Sasha Levin --- kernel/signal.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/signal.c b/kernel/signal.c index 072fd152ab01e..3095b2309876d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -71,6 +71,10 @@ static int sig_task_ignored(struct task_struct *t, int sig, bool force) handler = sig_handler(t, sig); + /* SIGKILL and SIGSTOP may not be sent to the global init */ + if (unlikely(is_global_init(t) && sig_kernel_only(sig))) + return true; + if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && handler == SIG_DFL && !(force && sig_kernel_only(sig))) return 1; -- 2.20.1