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 4DDCDC47254 for ; Tue, 5 May 2020 13:53:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 24EAF206A5 for ; Tue, 5 May 2020 13:53:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="I9RO3pgj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729134AbgEENxv (ORCPT ); Tue, 5 May 2020 09:53:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45320 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1728965AbgEENxu (ORCPT ); Tue, 5 May 2020 09:53:50 -0400 Received: from mail-pf1-x442.google.com (mail-pf1-x442.google.com [IPv6:2607:f8b0:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C2DD0C061A0F for ; Tue, 5 May 2020 06:53:50 -0700 (PDT) Received: by mail-pf1-x442.google.com with SMTP id x15so920730pfa.1 for ; Tue, 05 May 2020 06:53:50 -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=QJU1rgdyR3dsjV2URMfZxPtiLnMEVx7zziz4YW88wtc=; b=I9RO3pgjGmr1FZpr0FwTzwdMQZjnnQ/wVjovFIecF1T58ixbSFm2fJTWOqsJQ+QiHg OyJFLLZyE5MrODJ7pAmAy3cKW7fO7d9SZOH8/p55bXqM1ySA0LLe6GZ4LP9nHsoIhRBI 5TqYq3nNSBYoL+U8t/9YNBd2CVnf/oW0AKwN9Aj+dI0UVFEMsiM5iLDXSMIyiSyA0h7+ C6kWDkjUSP+ebxyGtTmhkRcALPduflyZwo1on3TtMGHfANUKwPXUSFUZt8NoZWV5s45v aSCOBUSupfNy1R/dN+O+5R0A4/Uc0YEUHBDJDnAcYaXZGx9D7Qt2Q1Z90tIDjrRTWhAH tFcA== 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=QJU1rgdyR3dsjV2URMfZxPtiLnMEVx7zziz4YW88wtc=; b=rz5VPNGgYxw4HxpF3uKYCjW874TjPD4P1HjaasZrbKofmvmjL8m45e2yOS2OwTDrsy fP+LkeRJyetPZm2H1njGbgF2PoGd2IRjY4TBgam8zplgsNpNyCbxf4fRt8/XO0Pw0m5Z zz8FnJDJku8dRYsFzCXcBOcKFuMHcP16TIoP0xvWtdDjwI2DMtwX99pDqV/QHGUnNCyY MrN8VJqjj9kikZhnqJ94SX77P2HgBhIVwT4kChhMiVWxa351A1R7d2aXVJ9ci8HvE4Iu PP1m6wK5bAdz9BWOfQGjRKeN23wd10TzktzPSOMPtKUp2c1ZoqdkTVvF+JtRqFZORR+X w/tw== X-Gm-Message-State: AGi0PuYTEbgdQCzM9fERGh/Hc8/4Gtk0/jaQnyS8lTnF7z/jcxoYFpLw benOgGySwtufDYuApdplVxlLq4ZvTNHYUQ== X-Google-Smtp-Source: APiQypJTpVbLFJfbC4pTfe+3bRqpJK6v1l7Gl1XmYpllcrZp8mtXHfu530JzQx2s1IZ5/Qt1u+NwBQ== X-Received: by 2002:a62:e51a:: with SMTP id n26mr3180048pff.301.1588686829155; Tue, 05 May 2020 06:53:49 -0700 (PDT) Received: from localhost.localdomain ([120.244.110.63]) by smtp.gmail.com with ESMTPSA id i15sm2061013pfo.195.2020.05.05.06.53.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 06:53:48 -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 21:53:13 +0800 Message-Id: <20200505135313.28793-1-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 is 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