From patchwork Tue Jun 9 23:26:26 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 28354 Return-Path: X-Original-To: patchwork-incoming@bilbo.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from ozlabs.org (ozlabs.org [203.10.76.45]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx.ozlabs.org", Issuer "CA Cert Signing Authority" (verified OK)) by bilbo.ozlabs.org (Postfix) with ESMTPS id E79DBB70B0 for ; Wed, 10 Jun 2009 09:27:35 +1000 (EST) Received: by ozlabs.org (Postfix) id D7C7CDDD0B; Wed, 10 Jun 2009 09:27:35 +1000 (EST) Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by ozlabs.org (Postfix) with ESMTP id 7F3B5DDD04 for ; Wed, 10 Jun 2009 09:27:35 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750810AbZFIX1b (ORCPT ); Tue, 9 Jun 2009 19:27:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753338AbZFIX1b (ORCPT ); Tue, 9 Jun 2009 19:27:31 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:41134 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750810AbZFIX1a (ORCPT ); Tue, 9 Jun 2009 19:27:30 -0400 Received: from imap1.linux-foundation.org (imap1.linux-foundation.org [140.211.169.55]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id n59NQQHE005955 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 9 Jun 2009 16:26:27 -0700 Received: from localhost.localdomain (localhost [127.0.0.1]) by imap1.linux-foundation.org (8.13.5.20060308/8.13.5/Debian-3ubuntu1.1) with ESMTP id n59NQQOQ014571; Tue, 9 Jun 2009 16:26:26 -0700 Message-Id: <200906092326.n59NQQOQ014571@imap1.linux-foundation.org> Subject: [patch 3/3] jbd: fix race in buffer processing in commit code To: torvalds@linux-foundation.org Cc: akpm@linux-foundation.org, jack@suse.cz, linux-ext4@vger.kernel.org, stable@kernel.org From: akpm@linux-foundation.org Date: Tue, 09 Jun 2009 16:26:26 -0700 X-Spam-Status: No, hits=-3.502 required=5 tests=AWL, BAYES_00, OSDL_HEADER_SUBJECT_BRACKETED X-Spam-Checker-Version: SpamAssassin 3.2.4-osdl_revision__1.47__ X-MIMEDefang-Filter: lf$Revision: 1.188 $ X-Scanned-By: MIMEDefang 2.63 on 140.211.169.13 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org From: Jan Kara In commit code, we scan buffers attached to a transaction. During this scan, we sometimes have to drop j_list_lock and then we recheck whether the journal buffer head didn't get freed by journal_try_to_free_buffers(). But checking for buffer_jbd(bh) isn't enough because a new journal head could get attached to our buffer head. So add a check whether the journal head remained the same and whether it's still at the same transaction and list. This is a nasty bug and can cause problems like memory corruption (use after free) or trigger various assertions in JBD code (observed). Signed-off-by: Jan Kara Cc: Cc: Signed-off-by: Andrew Morton --- fs/jbd/commit.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff -puN fs/jbd/commit.c~jbd-fix-race-in-buffer-processing-in-commit-code fs/jbd/commit.c --- a/fs/jbd/commit.c~jbd-fix-race-in-buffer-processing-in-commit-code +++ a/fs/jbd/commit.c @@ -241,7 +241,7 @@ write_out_data: spin_lock(&journal->j_list_lock); } /* Someone already cleaned up the buffer? */ - if (!buffer_jbd(bh) + if (!buffer_jbd(bh) || bh2jh(bh) != jh || jh->b_transaction != commit_transaction || jh->b_jlist != BJ_SyncData) { jbd_unlock_bh_state(bh); @@ -478,7 +478,9 @@ void journal_commit_transaction(journal_ spin_lock(&journal->j_list_lock); continue; } - if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) { + if (buffer_jbd(bh) && bh2jh(bh) == jh && + jh->b_transaction == commit_transaction && + jh->b_jlist == BJ_Locked) { __journal_unfile_buffer(jh); jbd_unlock_bh_state(bh); journal_remove_journal_head(bh);