Date: Wed, 8 Mar 2006 23:38:04 -0500
From: Dave Jones <davej@redhat.com>
To: "David S. Miller" <davem@davemloft.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: filldir[64] oddness
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On Wed, Mar 08, 2006 at 08:32:04PM -0800, David S. Miller wrote:
 > From: Dave Jones <davej@redhat.com>
 > Date: Wed, 8 Mar 2006 23:27:44 -0500
 > 
 > > #define NAME_OFFSET(de) ((int) ((de)->d_name - (char __user *) (de)))
 > > #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
 > > 
 > > 140  	static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 > > 141  			   ino_t ino, unsigned int d_type)
 > > 142  	{
 > > 143  		struct linux_dirent __user * dirent;
 > > 144  		struct getdents_callback * buf = (struct getdents_callback *) __buf
 > > 145  		int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 2);
 > > 
 > > How come that NAME_OFFSET isn't causing an oops when
 > > it dereferences stackjunk->d_name ?
 > 
 > d_name a char[] array, and we're just doing pointer arithmetic
 > here.  It's the same as "offsetof(d_name, struct linux_dirent)"
 > or something like that.

Duh, yes. Of course.

 > I think coverity is being trigger happy in this case :-)

agreed.

		Dave

-- 
http://www.codemonkey.org.uk
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