From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 6A7D07F4E for ; Thu, 15 Aug 2013 09:37:07 -0500 (CDT) Date: Thu, 15 Aug 2013 09:37:06 -0500 From: Ben Myers Subject: Re: [patch] xfs: check for underflow in xfs_iformat_fork() Message-ID: <20130815143706.GI7153@sgi.com> References: <20130815055338.GC23580@elgon.mountain> <520CA923.4060409@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <520CA923.4060409@oracle.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Dan Carpenter , Jeff Liu Cc: Alex Elder , kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, xfs@oss.sgi.com Hey Dan & Jeff, On Thu, Aug 15, 2013 at 06:10:43PM +0800, Jeff Liu wrote: > On 08/15/2013 01:53 PM, Dan Carpenter wrote: > > > The "di_size" variable comes from the disk and it's a signed 64 bit. > > We check the upper limit but we should check for negative numbers as > > well. > > > > Signed-off-by: Dan Carpenter > > > > diff --git a/fs/xfs/xfs_inode_fork.c b/fs/xfs/xfs_inode_fork.c > > index 123971b..849fc70 100644 > > --- a/fs/xfs/xfs_inode_fork.c > > +++ b/fs/xfs/xfs_inode_fork.c > > @@ -167,7 +167,8 @@ xfs_iformat_fork( > > } > > > > di_size = be64_to_cpu(dip->di_size); > > - if (unlikely(di_size > XFS_DFORK_DSIZE(dip, ip->i_mount))) { > > + if (unlikely(di_size < 0 || > > But the di_size is initialized to ZERO while allocating a new inode on disk. > I wonder if that is better to ASSERT in this case because the current check > is used to make sure that the item is inlined, or we don't need it at all. Hmm. Dan's additional check looks good to me. In this case I'd say the forced shutdown is more appropriate than an assert, because here we're reading the inode from disk, as opposed to looking at a structure that is already incore which we think we've initialized. We want to handle unexpected inputs from disk without crashing even if we are CONFIG_XFS_DEBUG. How did you come across this one? Reviewed-by: Ben Myers Regards, Ben _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs