linux-ext4 - Re: EXT4 panic at jbd2_journal_put_journal

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Sun, 12 May 2013 23:36:55 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Tony Luck <tony.luck@...il.com>
Cc:	eunb.song@...sung.com, Dmitry Monakhov <dmonakhov@...nvz.org>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: EXT4 panic at jbd2_journal_put_journal_head() in 3.9+

On Sun, May 12, 2013 at 08:11:59PM -0700, Tony Luck wrote:
> 
> My best guess as to why this commit causes problems is that there are places
> where updates to individual fields in this structure used to be independent
> because they were to whole words.  Now we have bitfileds there are races
> between access to different fields in the same word.

Yeah, except we access the fields while holding a lock.... wait a
minute.  We're using bit_spinlocks().... and am I missing something?

Where are the barrier statements to prevent the CPU or the compiler
from reordering statements around bit_spin_lock()?  But if that's the
problem, I would have expected lots of other things to be broken.

	   	      	       	       	     - 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