linux-kernel - Re: [PATCH] UDF: check for allocated memory for inode data

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Date:	Fri, 11 May 2007 11:49:03 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Christoph Hellwig <hch@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Ben Fennema <bfennema@...con.csc.calpoly.edu>,
	Jan Kara <jack@....cz>
Subject: Re: [PATCH] UDF: check for allocated memory for inode data

[Christoph Hellwig - Fri, May 11, 2007 at 08:29:39AM +0100]
| On Thu, May 10, 2007 at 03:46:40PM -0700, Andrew Morton wrote:
| > On Thu, 10 May 2007 18:00:00 +0400
| > Cyrill Gorcunov <gorcunov@...il.com> wrote:
| > 
| > > This patch adds cheking for granted memory while
| > > filling up inode data to prevent possible NULL
| > > pointer usage. If there is not enough memory to
| > > fill inode data we just mark it as "bad".
| > > 
| > > Signed-off-by: Cyrill Gorcunov <gorcunov@...il.com>
| > > 
| > > Please check the patch, maybe just marking inode as
| > > "bad" is not a good solution.
| > > 
| > 
| > yes, make_bad_inode() is appropriate here.
| > 
| > > 
| > > diff --git a/fs/udf/inode.c b/fs/udf/inode.c
| > > index c846155..91cddae 100644
| > > --- a/fs/udf/inode.c
| > > +++ b/fs/udf/inode.c
| > > @@ -1144,6 +1144,13 @@ static void udf_fill_inode(struct inode *inode, struct buffer_head *bh)
| > >  		UDF_I_EFE(inode) = 1;
| > >  		UDF_I_USE(inode) = 0;
| > >  		UDF_I_DATA(inode) = kmalloc(inode->i_sb->s_blocksize - sizeof(struct extendedFileEntry), GFP_KERNEL);
| > > +		if (!UDF_I_DATA(inode))
| > > +		{
| > > +			printk(KERN_ERR "udf: udf_fill_inode(ino %ld) no free memory\n",
| > > +			       inode->i_ino);
| > > +			make_bad_inode(inode);
| > > +			return;
| > > +		}
| > 
| > But please let's not add three copies of identical code.  Do something like:
| > 
| > static int udf_check_inode(struct inode *inode)
| > {
| > 	if (!UDF_I_DATA(inode)) {
| > 		printk(KERN_ERR "udf: udf_fill_inode(ino %ld) no free memory\n",
| > 			inode->i_ino);
| > 		make_bad_inode(inode);
| > 		return -1;
| > 	}
| > 	return 0;
| > }
| > 
| > 
| > 	if (udf_check_inode(inode))
| > 		return;
| > 
| > In fact you can also do the kmalloc in that helper function too:
| > 
| > static int udf_alloc_i_data(struct inode *inode, size_t size)
| > {
| > 	UDF_I_DATA(inode) = kmalloc(...);
| > 	...
| > }
| 
| And please get rid of the UDF_I_* macro for everything you touch, just
| put a
| 
| 	struct udf_inode_info *uip = UDF_I(inode);
| 
| at the beginning of the function and use the fields directly.
| 

OK, I've already sent v.2 of the patch, so v.3 will become soon ;)

		Cyrill

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