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 DF083C43215 for ; Tue, 19 Nov 2019 05:59:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9A5C222C7 for ; Tue, 19 Nov 2019 05:59:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574143160; bh=ZD0xjZxf+rBGGbulxvdMIUcuFcIPAo9Xn7A7JcL8GCg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=O3M00OODBj1ooC2i0YioewFh7h+arFAC2VZeIVVRamVuqC9lLQqRof4hSFBPuYJl7 ceFHDl+WaENOODWSYHTTW8u/FygwbJraBdUo3ORo+ueX+4h4JNT7ejCp4Rn1NnssfU RaWuM85csfzm989hJndEjZaNhAjytALMb4I1UGEY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731289AbfKSFrx (ORCPT ); Tue, 19 Nov 2019 00:47:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:44120 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730978AbfKSFrp (ORCPT ); Tue, 19 Nov 2019 00:47:45 -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 BFF4F208C3; Tue, 19 Nov 2019 05:47:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574142464; bh=ZD0xjZxf+rBGGbulxvdMIUcuFcIPAo9Xn7A7JcL8GCg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mVDylcLy2MzlnRY+QXIbCv4efRawyixXg8KmhEYae5/or1hgNoPRcGIHX4ecqplNs msxKv9VuSaNDRlR1Obdprx0NCJAISRi/jNK9Jtz2FChY166dfrDiTaJxAlai4YPiNS QxGWuKqraTAMUGNEe4R6iFykEiVjAFJRi+IDy+eM= 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 4.14 091/239] signal: Always ignore SIGKILL and SIGSTOP sent to the global init Date: Tue, 19 Nov 2019 06:18:11 +0100 Message-Id: <20191119051319.779339966@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191119051255.850204959@linuxfoundation.org> References: <20191119051255.850204959@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 bb801156628ee..c9b203875001e 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -77,6 +77,10 @@ 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