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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 57E2BCA9EBD for ; Fri, 25 Oct 2019 18:09:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 378D121D7F for ; Fri, 25 Oct 2019 18:09:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733254AbfJYSIx (ORCPT ); Fri, 25 Oct 2019 14:08:53 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:46872 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731490AbfJYSFo (ORCPT ); Fri, 25 Oct 2019 14:05:44 -0400 Received: from [167.98.27.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1iO3xv-0008OG-Ph; Fri, 25 Oct 2019 19:05:35 +0100 Received: from ben by deadeye with local (Exim 4.92.2) (envelope-from ) id 1iO3xu-0001hs-Ug; Fri, 25 Oct 2019 19:05:34 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Daniel Lezcano" , "Eric W. Biederman" , "Oleg Nesterov" , "Serge Hallyn" Date: Fri, 25 Oct 2019 19:03:06 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 05/47] signal/pid_namespace: Fix reboot_pid_ns to use send_sig not force_sig In-Reply-To: X-SA-Exim-Connect-IP: 167.98.27.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.76-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "Eric W. Biederman" commit f9070dc94542093fd516ae4ccea17ef46a4362c5 upstream. The locking in force_sig_info is not prepared to deal with a task that exits or execs (as sighand may change). The is not a locking problem in force_sig as force_sig is only built to handle synchronous exceptions. Further the function force_sig_info changes the signal state if the signal is ignored, or blocked or if SIGNAL_UNKILLABLE will prevent the delivery of the signal. The signal SIGKILL can not be ignored and can not be blocked and SIGNAL_UNKILLABLE won't prevent it from being delivered. So using force_sig rather than send_sig for SIGKILL is confusing and pointless. Because it won't impact the sending of the signal and and because using force_sig is wrong, replace force_sig with send_sig. Cc: Daniel Lezcano Cc: Serge Hallyn Cc: Oleg Nesterov Fixes: cf3f89214ef6 ("pidns: add reboot_pid_ns() to handle the reboot syscall") Signed-off-by: "Eric W. Biederman" Signed-off-by: Ben Hutchings --- kernel/pid_namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -304,7 +304,7 @@ int reboot_pid_ns(struct pid_namespace * } read_lock(&tasklist_lock); - force_sig(SIGKILL, pid_ns->child_reaper); + send_sig(SIGKILL, pid_ns->child_reaper, 1); read_unlock(&tasklist_lock); do_exit(0);