From: "Duane Griffin" Subject: Re: jbd2-abort-instead-of-waiting-for-nonexistent-transactions.patch Date: Mon, 29 Sep 2008 17:51:13 +0100 Message-ID: <20080929165113.GA1360@dastardly.home.dghda.com> References: <20080922140851.bc3f9319.akpm@linux-foundation.org> <20080929022426.GL8711@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Duane Griffin , Andrew Morton , "Stephen C. Tweedie" , linux-ext4@vger.kernel.org To: Theodore Tso Return-path: Received: from kumera.dghda.com ([80.68.90.171]:2246 "EHLO kumera.dghda.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751897AbYI2Q6A (ORCPT ); Mon, 29 Sep 2008 12:58:00 -0400 Content-Disposition: inline In-Reply-To: <20080929022426.GL8711@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sun, Sep 28, 2008 at 10:24:26PM -0400, Theodore Tso wrote: > On Tue, Sep 23, 2008 at 05:56:27PM +0100, Duane Griffin wrote: > > Stephen suggested that it would be better to sanity check the journal > > start/end pointers on mount, rather than catching the error later like > > this. I never quite convinced myself I'd worked out the right way to > > do that, sorry. Perhaps someone would like to confirm (or otherwise) > > whether or not the following is correct: > > > > In journal_reset (?) check that: > > > > journal->j_first == 1 (this seems to be the only valid value) > > > > and > > > > journal->j_last >= JFS_MIN_JOURNAL_BLOCKS > > Yes, for all existing currently created, j_first will be 1. I can't > think of a good reason for why we might want to reserve some space at > the beginning of the journal, but the safest check would be: > > (journal->j_last - journal->j_first +1) >= JFS_MIN_JOURNAL_BLOCKS Fair enough. > > Additionally, it should be possible to check the journal->j_last more > > precisely. For internal journals it seems straight-forward, we can > > just check that journal->j_last == inode->i_size >> > > inode->i_sb->s_blocksize_bits. For external journals we'd need to load > > the device's superblock and check journal->j_last == s_blocks_count. > > Yep, agreed. OK, great. See patch below. I'll send the ext3/jbd version once you're happy with it. > > Regardless, I think the original patch may be a good idea. It improves > > robustness and matches the other locations where we call > > jbd2_log_do_checkpoint. They are all in loops that test that > > journal->j_checkpoint_transactions != NULL. > > Agreed. I've included it in the ext4 patch queue, and will be soon > putting out a new ext4 patchset consisting of the patches I plan to > push during the next merge window. Great, thanks. The original patch was for ext3/jbd patch, but I'm not sure whether that has been accepted anywhere or not. I'll check after the ext3 patches are merged and resend it if needed. > - Ted Cheers, Duane. -- Subject: [PATCH] jbd2: sanity check block range Invalid journal start/end block values can cause BUGs. Do some sanity checking on them when we load the journal. Signed-off-by: Duane Griffin --- diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index 8207a01..bb926e4 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -41,6 +41,8 @@ #include #include +#include "../ext4/ext4.h" + EXPORT_SYMBOL(jbd2_journal_start); EXPORT_SYMBOL(jbd2_journal_restart); EXPORT_SYMBOL(jbd2_journal_extend); @@ -1120,6 +1122,34 @@ static void journal_fail_superblock (journal_t *journal) journal->j_sb_buffer = NULL; } +static int validate_last_block(journal_t *journal, unsigned long last) +{ + if (journal->j_inode) { + return last == journal->j_inode->i_size >> + journal->j_inode->i_sb->s_blocksize_bits; + } else { + struct buffer_head *bh; + struct ext4_super_block *es; + ext4_fsblk_t sb_block; + ext4_fsblk_t count; + unsigned long offset; + + sb_block = EXT4_MIN_BLOCK_SIZE / journal->j_blocksize; + offset = EXT4_MIN_BLOCK_SIZE % journal->j_blocksize; + bh = __getblk(journal->j_dev, sb_block, journal->j_blocksize); + if (bh) { + es = (struct ext4_super_block *) bh->b_data + offset; + count = ext4_blocks_count(es); + brelse(bh); + return count == last; + } else { + printk(KERN_WARNING + "JBD2: IO error reading journal's ext3 sb\n"); + return 0; + } + } +} + /* * Given a journal_t structure, initialise the various fields for * startup of a new journaling session. We use this both when creating @@ -1134,6 +1164,16 @@ static int journal_reset(journal_t *journal) first = be32_to_cpu(sb->s_first); last = be32_to_cpu(sb->s_maxlen); + if (last - first + 1 < JBD2_MIN_JOURNAL_BLOCKS) { + printk(KERN_ERR "JBD2: Bad journal block range: %llu-%llu\n", + first, last); + return -EIO; + } + + if (!validate_last_block(journal, last)) { + printk(KERN_ERR "JBD2: Bad last journal block: %llu\n", last); + return -EIO; + } journal->j_first = first; journal->j_last = last;