From patchwork Tue Jun 23 10:54:45 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: wang yanqing X-Patchwork-Id: 6659731 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 1C93F9F39B for ; Tue, 23 Jun 2015 11:28:10 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 3B2A620454 for ; Tue, 23 Jun 2015 11:28:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63F602041F for ; Tue, 23 Jun 2015 11:28:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753765AbbFWL1y (ORCPT ); Tue, 23 Jun 2015 07:27:54 -0400 Received: from mail-pd0-f174.google.com ([209.85.192.174]:33787 "EHLO mail-pd0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751256AbbFWL1w (ORCPT ); Tue, 23 Jun 2015 07:27:52 -0400 Received: by pdjn11 with SMTP id n11so5536505pdj.0; Tue, 23 Jun 2015 04:27:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc:subject:message-id:mail-followup-to:mime-version :content-type:content-disposition:user-agent; bh=qj75ws+CGEgQa27+8Y/u5zRBQ9REr0EimFY3roX32rY=; b=q+cCkIqh+UNYbleuPJ+W5RU8Kkhl0AGCJFgo50kO0n/BrwZDt7MUdO+kDQC5IeO5mB 7Z34YMIT+8ZJisxGRUmJp9dy6y7Lr/V6yUQrmVUSnbqdlZixfpVoUftBoEHY3KUHtNR5 +5PrmzzZIAQkM99I5TRURoQ+zXSd4hJsj4gDCzjWt4jetY9u+TGuOwgz0gLYNBEAUGnT 6Zfn48GzLFGkV1FIZk+TBac5W6ZUUR9mOE8CJiFrNhmEqUvBXDzZeliHUegKPrhau9MI X70cLM5FNOZXp9SCyPCC80wsJ/LWIdUO8KlLSQzncMTICXOEv0lze9o/GOasnaW7x8gn CXUg== X-Received: by 10.66.249.198 with SMTP id yw6mr67335182pac.149.1435058872093; Tue, 23 Jun 2015 04:27:52 -0700 (PDT) Received: from udknight.localhost ([120.42.91.226]) by mx.google.com with ESMTPSA id c7sm22911228pbu.60.2015.06.23.04.27.50 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 23 Jun 2015 04:27:51 -0700 (PDT) Received: from udknight.localhost (udknight.com [127.0.0.1]) by udknight.localhost (8.14.4/8.14.4) with ESMTP id t5NAsjKk006808; Tue, 23 Jun 2015 18:54:45 +0800 Received: (from root@localhost) by udknight.localhost (8.14.4/8.14.4/Submit) id t5NAsjcn006805; Tue, 23 Jun 2015 18:54:45 +0800 Date: Tue, 23 Jun 2015 18:54:45 +0800 From: Wang YanQing To: viro@zeniv.linux.org.uk Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation Message-ID: <20150623105445.GA6746@udknight.ahead-top.com> Mail-Followup-To: Wang YanQing , viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.22 (2013-10-16) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-8.2 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Execution of get_anon_bdev concurrently and preemptive kernel all could bring race condition, it isn't enough to check dev against its upper limitation with equality operator only. This patch fix it. Signed-off-by: Wang YanQing --- fs/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/super.c b/fs/super.c index 928c20f..b613723 100644 --- a/fs/super.c +++ b/fs/super.c @@ -842,7 +842,7 @@ int get_anon_bdev(dev_t *p) else if (error) return -EAGAIN; - if (dev == (1 << MINORBITS)) { + if (dev >= (1 << MINORBITS)) { spin_lock(&unnamed_dev_lock); ida_remove(&unnamed_dev_ida, dev); if (unnamed_dev_start > dev)