linux-ext4 - Re: jbd2-abort-instead-of-waiting-for-nonexistent-transactions.patch

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 28 Sep 2008 22:24:26 -0400
From:	Theodore Tso <tytso@....edu>
To:	Duane Griffin <duaneg@...da.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	"Stephen C. Tweedie" <sct@...hat.com>, linux-ext4@...r.kernel.org
Subject: Re:
	jbd2-abort-instead-of-waiting-for-nonexistent-transactions.patch

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

> 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.

> 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.

						- Ted
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html