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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 D8C57C71122 for ; Sun, 14 Oct 2018 15:36:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AAFD020835 for ; Sun, 14 Oct 2018 15:36:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AAFD020835 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728884AbeJNXRc (ORCPT ); Sun, 14 Oct 2018 19:17:32 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36687 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727252AbeJNXRc (ORCPT ); Sun, 14 Oct 2018 19:17:32 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1gBiME-0004cm-PR; Sun, 14 Oct 2018 16:31:06 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gBiLP-0000Dg-B2; Sun, 14 Oct 2018 16:30:15 +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, "Davidlohr Bueso" , "Manfred Spraul" , "Linus Torvalds" , "Davidlohr Bueso" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 063/366] ipc,shm: move BUG_ON check into shm_lock In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 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 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Davidlohr Bueso commit c5c8975b2eb4eb7604e8ce4f762987f56d2a96a2 upstream. Upon every shm_lock call, we BUG_ON if an error was returned, indicating racing either in idr or in shm_destroy. Move this logic into the locking. [akpm@linux-foundation.org: simplify code] Signed-off-by: Davidlohr Bueso Cc: Manfred Spraul Cc: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- ipc/shm.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/ipc/shm.c +++ b/ipc/shm.c @@ -155,8 +155,11 @@ static inline struct shmid_kernel *shm_l { struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id); - if (IS_ERR(ipcp)) - return (struct shmid_kernel *)ipcp; + /* + * We raced in the idr lookup or with shm_destroy(). Either way, the + * ID is busted. + */ + BUG_ON(IS_ERR(ipcp)); return container_of(ipcp, struct shmid_kernel, shm_perm); } @@ -190,7 +193,6 @@ static void shm_open(struct vm_area_stru struct shmid_kernel *shp; shp = shm_lock(sfd->ns, sfd->id); - BUG_ON(IS_ERR(shp)); shp->shm_atim = get_seconds(); shp->shm_lprid = task_tgid_vnr(current); shp->shm_nattch++; @@ -256,7 +258,6 @@ static void shm_close(struct vm_area_str down_write(&shm_ids(ns).rwsem); /* remove from the list of attaches of the shm segment */ shp = shm_lock(ns, sfd->id); - BUG_ON(IS_ERR(shp)); shp->shm_lprid = task_tgid_vnr(current); shp->shm_dtim = get_seconds(); shp->shm_nattch--; @@ -1199,7 +1200,6 @@ out_fput: out_nattch: down_write(&shm_ids(ns).rwsem); shp = shm_lock(ns, shmid); - BUG_ON(IS_ERR(shp)); shp->shm_nattch--; if (shm_may_destroy(ns, shp)) shm_destroy(ns, shp);