From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [PATCH] vfs: check value of varaiable 'nd' before using its
 member
Date: Wed, 4 Jul 2012 19:30:13 +0100
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References: <1341394364-32289-1-git-send-email-robin.k.dong@gmail.com>
 <1341394749.2739.2.camel@menhir>
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Cc: Robin Dong <robin.k.dong@gmail.com>, linux-fsdevel@vger.kernel.org,
	Robin Dong <sanbai@taobao.com>
To: Steven Whitehouse <swhiteho@redhat.com>
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On Wed, Jul 04, 2012 at 10:39:09AM +0100, Steven Whitehouse wrote:
> Hi,
> 
> On Wed, 2012-07-04 at 17:32 +0800, Robin Dong wrote:
> > From: Robin Dong <sanbai@taobao.com>
> > 
> > When we using lookup_one_len() to search pathname component, it will call __lookup_hash()
> > with variable 'nd' as NULL :
> > 
> > 	--> __lookup_hash ( nd = NULL )
> > 		--> lookup_dcache
> > 			--> d_invalidate
> > 				--> proc_sys_revalidate
> > 
> > the proc_sys_revalidate will use 'nd->flags' before check whether its value is NULL.
> > This will cause kernel panic.
> > 
> > Therefore, we should adding check-code for filesystems which directly use nd->flags.
> > 
> > Signed-off-by: Robin Dong <sanbai@taobao.com>
> 
> nd will very shortly no longer be passed to revalidate... see this patch
> in Al's vfs git tree:
> 

Not to mention that anyone who tries to export procfs over nfs deserves Bad Things(tm)
happening to them....

IOW, what the hell is your code trying to do?