linux-kernel - Re: [fs] inode_lru_isolate(): Move counter increment into spinlock section

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:	Thu, 19 Dec 2013 15:23:22 +1100
From:	Dave Chinner <david@...morbit.com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Dave Chinner <dchinner@...hat.com>, linux-kernel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [fs] inode_lru_isolate(): Move counter increment into spinlock
 section

On Wed, Dec 18, 2013 at 07:24:46PM +0000, Christoph Lameter wrote:
> The counter increment in inode_lru_isolate is happening after
> spinlocks have been dropped with preemption on using __count_vm_events
> making counter increment races possible.

That's a nasty, undocumented problem that __count_vm_events() has.
Nobody who is modifying the fs/inode.c code is likely to know about
this, so just moving the code under an unrelated lock is not
sufficient to prevent this from happening again. Hence I'd prefer
that you just change it to use count_vm_events() rather than try to
be tricksy by replacing the landmine in the code that we've already
stepped on once.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/