From: Subject: patch jbd-fix-race-in-buffer-processing-in-commit-code.patch added to 2.6.29-stable tree Date: Mon, 29 Jun 2009 10:46:52 -0700 Message-ID: <20090629174714.95D2348FF0@coco.kroah.org> Cc: , To: jack@suse.cz, akpm@linux-foundation.org, gregkh@suse.de, linux-ext4@vger.kernel.org, torvalds@linux-foundation.org Return-path: Received: from kroah.org ([198.145.64.141]:50325 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754204AbZF2RrL (ORCPT ); Mon, 29 Jun 2009 13:47:11 -0400 Sender: linux-ext4-owner@vger.kernel.org List-ID: This is a note to let you know that we have just queued up the patch titled Subject: jbd: fix race in buffer processing in commit code to the 2.6.29-stable tree. Its filename is jbd-fix-race-in-buffer-processing-in-commit-code.patch A git repo of this tree can be found at http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary >From a61d90d75d0f9e86432c45b496b4b0fbf0fd03dc Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 9 Jun 2009 16:26:26 -0700 Subject: jbd: fix race in buffer processing in commit code 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(-) --- 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); Patches currently in stable-queue which might be from jack@suse.cz are queue-2.6.29/jbd-fix-race-in-buffer-processing-in-commit-code.patch