From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030195AbWGSPy4 (ORCPT ); Wed, 19 Jul 2006 11:54:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030196AbWGSPy4 (ORCPT ); Wed, 19 Jul 2006 11:54:56 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:58838 "EHLO atrey.karlin.mff.cuni.cz") by vger.kernel.org with ESMTP id S1030195AbWGSPyz (ORCPT ); Wed, 19 Jul 2006 11:54:55 -0400 Date: Wed, 19 Jul 2006 17:55:02 +0200 From: Jan Kara To: James <20@madingley.org> Cc: Marcel Holtmann , linux-kernel@vger.kernel.org, akpm@osdl.org, sct@redhat.com Subject: Re: Bad ext3/nfs DoS bug Message-ID: <20060719155502.GD3270@atrey.karlin.mff.cuni.cz> References: <20060717130128.GA12832@circe.esc.cam.ac.uk> <1153209318.26690.1.camel@localhost> <20060718145614.GA27788@circe.esc.cam.ac.uk> <1153236136.10006.5.camel@localhost> <20060718152341.GB27788@circe.esc.cam.ac.uk> <1153253907.21024.25.camel@localhost> <20060719092810.GA4347@circe.esc.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060719092810.GA4347@circe.esc.cam.ac.uk> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > So what happens next? Is the ext3 maintainer on sabatical, > or am I expected to submit a patch to fix this? I guess people are mostly busy with OLS and such so maybe they missed the discussion.. Giving CC to relevant people to catch their attention :) Andrew, Stephen: James has come across a nasty bug (potentially remote DoS). NFS extracts inode number from a filehandle and the inode number eventually ends in ext3_read_inode(). Now if the inode number is bogus, ext3_get_inode_block() calls ext3_error() and filesystem is remounted RO or whatever else is configured. That is quite undesirable in this case. Now the easy "fix" is to change ext3_error() to ext3_warning() but an attacker flooding your logs with warnings is probably not good either and in case the inode number comes from ext3 itself we should really do ext3_error() as there is some corruption in the fs. Better fix would be to add a flag to read_inode() saying that the inode number is from untrusted source (but that means changing a prototype of a function every fs uses) and change export_iget() to pass this flag. Yet another solution would be to make ext3 implement its own get_dentry() export function and pass the flag internally... What do you think is the best solution? Honza -- Jan Kara SuSE CR Labs