From patchwork Wed Jul 1 00:14:00 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: gregkh@suse.de X-Patchwork-Id: 29333 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 2BF9CB70DC for ; Wed, 1 Jul 2009 11:32:22 +1000 (EST) Received: by ozlabs.org (Postfix) id 665F1DDDFC; Wed, 1 Jul 2009 10:32:57 +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 E71F5DDDFB for ; Wed, 1 Jul 2009 10:32:56 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760830AbZGAAcj (ORCPT ); Tue, 30 Jun 2009 20:32:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760859AbZGAAcj (ORCPT ); Tue, 30 Jun 2009 20:32:39 -0400 Received: from kroah.org ([198.145.64.141]:59733 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760821AbZGAAci (ORCPT ); Tue, 30 Jun 2009 20:32:38 -0400 Received: from localhost (c-76-105-230-205.hsd1.or.comcast.net [76.105.230.205]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by coco.kroah.org (Postfix) with ESMTPSA id 676D549126; Tue, 30 Jun 2009 17:32:41 -0700 (PDT) X-Mailbox-Line: From gregkh@mini.kroah.org Tue Jun 30 17:15:48 2009 Message-Id: <20090701001548.636200762@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Tue, 30 Jun 2009 17:14:00 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jan Kara , Subject: [patch 04/35] jbd: fix race in buffer processing in commit code References: <20090701001356.007288418@mini.kroah.org> Content-Disposition: inline; filename=jbd-fix-race-in-buffer-processing-in-commit-code.patch Lines: 48 In-Reply-To: <20090701002825.GA6518@kroah.com> Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org 2.6.29-stable review patch. If anyone has any objections, please let us know. ------------------ From: Jan Kara commit a61d90d75d0f9e86432c45b496b4b0fbf0fd03dc upstream. 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: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/jbd/commit.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html --- a/fs/jbd/commit.c +++ b/fs/jbd/commit.c @@ -238,7 +238,7 @@ 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); @@ -466,7 +466,9 @@ 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);