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 078CCC5DF60 for ; Fri, 8 Nov 2019 11:41:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7C98222CE for ; Fri, 8 Nov 2019 11:41:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573213276; bh=gqF0Xk1DbU2gg9xKC0sPCvRiCbjg6vSi0Iu0g9ztgMQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=uDY44UsuMLij4ZjJIVdfxo2+Lwtk1YnXB7y4wod4dyC7q4ioer0JTwc3DKteeimQl lJDtlwOVidAbOwKQAMwpehrh5f6YhBDNf4iDfqjTqqpfK6TGKCFoPbryjfObIBC8Wm q9IK6Vf1rk7Ell/wnJufm5Q6bPYKCKIVKGLEn/cY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389260AbfKHLlP (ORCPT ); Fri, 8 Nov 2019 06:41:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:54322 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389195AbfKHLlI (ORCPT ); Fri, 8 Nov 2019 06:41:08 -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 D09ED21D6C; Fri, 8 Nov 2019 11:41:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573213268; bh=gqF0Xk1DbU2gg9xKC0sPCvRiCbjg6vSi0Iu0g9ztgMQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=agqHCrROlrbRL/o00ysRtB5unBu5DNkkW8yhme6N6lsZENDfnlK16ObzRdjQCsXm6 u22SMtEAsh610ymnwt1647aGOTZEZVlKA0kw6xtu2p+UfKocC2kwqXLyV+6e/CHeCo kdhPJ4nxha9c3EU8ig/cX9AmqpSYnrEa1Ye9VWJQ= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Eric W. Biederman" , Thomas Gleixner , Sasha Levin Subject: [PATCH AUTOSEL 4.19 131/205] signal: Always ignore SIGKILL and SIGSTOP sent to the global init Date: Fri, 8 Nov 2019 06:36:38 -0500 Message-Id: <20191108113752.12502-131-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191108113752.12502-1-sashal@kernel.org> References: <20191108113752.12502-1-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 0e6bc3049427e..7278302e34850 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -78,6 +78,10 @@ static bool 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 true; -- 2.20.1