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=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 3D943C47247 for ; Tue, 5 May 2020 14:50:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 116CC206B9 for ; Tue, 5 May 2020 14:50:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="loAfKpvr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729398AbgEEOuF (ORCPT ); Tue, 5 May 2020 10:50:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54514 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729060AbgEEOuF (ORCPT ); Tue, 5 May 2020 10:50:05 -0400 Received: from mail-pj1-x1043.google.com (mail-pj1-x1043.google.com [IPv6:2607:f8b0:4864:20::1043]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63D39C061A0F for ; Tue, 5 May 2020 07:50:03 -0700 (PDT) Received: by mail-pj1-x1043.google.com with SMTP id q24so469432pjd.1 for ; Tue, 05 May 2020 07:50:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=FHjXPsU26H0OF2JRAex/ddIqer39oiBwJgvFSKTEKIY=; b=loAfKpvrXy8JZk/co9QVvVYUvjTD5FZP/X51udmNZb9CVrPWUPLJjgkVeX4yzMNuos i4s9co+v9pPLXg7fiTwT8CjSc7DvVUck2Pw5Il4WWHdId9tQN417sNnw+0dnKWo/srlQ tCcXviaPvUcA2ReZgq+YemUOsAIppGo9k+H+EGZmfugrabUOZD8RZDeKTvWEKHTvciss OXYim4bYgvD2sSoUH99mEJ4Rr0zPYRIbmMTpXm7a2M2P/s3ukqKIgrE3KS2mDbf06dt3 IJQYwsmGwUj1njTjH9KNy5V9q+ZVw39HViCX6XuXZ20ONqc4h3HKcCv2FfRS+Xpc0TNr GcYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=FHjXPsU26H0OF2JRAex/ddIqer39oiBwJgvFSKTEKIY=; b=IxFXZM6Cjm21Xw7uFh9lEwMfS/eFwXvMfuNLIjAXDggHYjEMCxOgBGW2R2iCz5PpRL 6pX5Tgr21/KjeQTvwNui/PUpXR7Qg0ems96zi/DpK35Syg8+iUm5qvnYZSCmYgpOaiJj NfPk2g6ruPtOtHQbe8NlY+eS9wpvR9WBo7F0T7ZbzYSzwCLjfmn7o5ZgArOLO8S8Gxqa P9h3Mr8UdYRDdnVTO4vEcSE+07gv11CE3kQDfwnk3bM8rSwE1UUoujrlK6w5jXV3JWly FzPZ9Cd89Uq9iiU4qrS66nC0kxaUK+nfAQ0st71zuGzdO2dcQOFwAN/1K5+84PjszzLh 5q7g== X-Gm-Message-State: AGi0Pua15sJWDcvp8NUntqTQxsPec6u1UXtqTexlvne8EvbsJe3k2AKD A1ay5qrRKvMWx60LiunJK8c5xue+5BUN0Q== X-Google-Smtp-Source: APiQypIQMNjcbl+8Wcw3aymz/pGlaLzA8y3jtrAd6BgNWxq7pxYsvDuca1/u9Gn2cd0YEexhcSq+bg== X-Received: by 2002:a17:90a:2645:: with SMTP id l63mr3610638pje.54.1588690202879; Tue, 05 May 2020 07:50:02 -0700 (PDT) Received: from localhost.localdomain ([120.244.110.63]) by smtp.gmail.com with ESMTPSA id c84sm2288400pfb.153.2020.05.05.07.49.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 07:50:02 -0700 (PDT) From: Jia-Ju Bai To: shaggy@kernel.org, Markus.Elfring@web.de Cc: jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org, Jia-Ju Bai Subject: [PATCH v2] fs: jfs: fix a possible data race in metapage_writepage() Date: Tue, 5 May 2020 22:49:30 +0800 Message-Id: <20200505144930.7990-1-baijiaju1990@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The functions metapage_writepage() and lmPostGC() can be concurrently executed in the following call contexts: Thread1: metapage_writepage() Thread2: lbmIODone() lmPostGC() In metapage_writepage(): if (mp->log && !(mp->log->cflag & logGC_PAGEOUT)) In lmPostGC(): spin_lock_irqsave(&log->gclock, flags); ... log->cflag &= ~logGC_PAGEOUT ... spin_unlock_irqrestore(&log->gclock, flags); The memory addresses of mp->log->cflag and log->cflag can be identical, and thus a data race can occur. This data race was found by our concurrency fuzzer. Thus use the spin lock "mp->log->gclock" for the assignment of the data structure member "log->cflag" to a local variable in this function implementation. Signed-off-by: Jia-Ju Bai --- v2: * Change the description. Thank Markus Elfring for good advice. fs/jfs/jfs_metapage.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c index a2f5338a5ea1..026c11b2572d 100644 --- a/fs/jfs/jfs_metapage.c +++ b/fs/jfs/jfs_metapage.c @@ -351,6 +351,7 @@ static int metapage_writepage(struct page *page, struct writeback_control *wbc) unsigned long bio_offset = 0; int offset; int bad_blocks = 0; + uint cflag; page_start = (sector_t)page->index << (PAGE_SHIFT - inode->i_blkbits); @@ -370,8 +371,14 @@ static int metapage_writepage(struct page *page, struct writeback_control *wbc) * Make sure this page isn't blocked indefinitely. * If the journal isn't undergoing I/O, push it */ - if (mp->log && !(mp->log->cflag & logGC_PAGEOUT)) - jfs_flush_journal(mp->log, 0); + + if (mp->log) { + spin_lock_irq(&mp->log->gclock); + cflag = mp->log->cflag; + spin_unlock_irq(&mp->log->gclock); + if (!(cflag & logGC_PAGEOUT)) + jfs_flush_journal(mp->log, 0); + } continue; } -- 2.17.1