Re: filldir[64] oddness

[Stephen Rothwell]

On Wed, 8 Mar 2006 23:27:44 -0500 Dave Jones <davej@xxxxxxxxxx> wrote:
>
> I'm puzzled by an aparent use of uninitialised memory
> that coverity's checker picked up.
> 
> fs/readdir.c
> 
> #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 ?

because d_name is an array, so the reference is really &(dirent->d_name[0]) and no
dereference occurs ...

-- 
Cheers,
Stephen Rothwell                    sfr@xxxxxxxxxxxxxxxx
http://www.canb.auug.org.au/~sfr/

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