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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 A5F2AC5DF60 for ; Fri, 8 Nov 2019 11:58:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 74397215EA for ; Fri, 8 Nov 2019 11:58:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573214283; bh=TbNX3dN2mRRR9GX73JiJ7PChGNt7lFxgYfJmfZAb+A4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=YhZjMl7VktyVAYuIdHen98u+fcb/rCBFF7p6O5AWr+QCQIggDHX3ozZ+rHJ96tV1D nNOqXE09pY2PiFGueYp2p6R8royY0s5Xr4y3p5kon25flKJmHVPOtmWB3u2n105ecU LpXiPAetVNfezNY5x6ZuFKTlnrhVY1+8B6iUR5wk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390920AbfKHLov (ORCPT ); Fri, 8 Nov 2019 06:44:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:59746 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390877AbfKHLoo (ORCPT ); Fri, 8 Nov 2019 06:44:44 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0473A222D1; Fri, 8 Nov 2019 11:44:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573213483; bh=TbNX3dN2mRRR9GX73JiJ7PChGNt7lFxgYfJmfZAb+A4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X1vh878hdL1hkOkXKCbadKlU9aeCeRD2M1ZIfqlb8zVXPqi+vaaSrqvRCuvQGeVMX DaplhibDNFOT6Ul8klUIFDCzSifOrFd/hbwb7n+mMxZVfj/MgDmtNZl3JqdknJn2bd YQ8T/YOMiOf9VAQe0J+Vw44d1klY3oNWSOYAjbU4= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Eric W. Biederman" , Thomas Gleixner , Sasha Levin Subject: [PATCH AUTOSEL 4.14 064/103] signal: Always ignore SIGKILL and SIGSTOP sent to the global init Date: Fri, 8 Nov 2019 06:42:29 -0500 Message-Id: <20191108114310.14363-64-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191108114310.14363-1-sashal@kernel.org> References: <20191108114310.14363-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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