Re: copy_from_user() fix
H. Peter Anvin (hpa@transmeta.com)
Thu, 27 Aug 1998 04:53:09 -0700 (PDT)
> (off-list)
>
> H. Peter Anvin wrote:
> > Not necessarily fast, if the region is large, though; but it's still
> > faster than anything that involves a system call (especially since the
> > kernel does the effectively same thing.)
>
> Think again... when you do the write to /dev/zero, it will do the verify_area
> once, and then return either EFAULT or the number of bytes... since /dev/zero
> doesn't actually do any access it shouldn't ever read the data in RAM
> (or am I missing something? this is definately how it *should* work I'd
> think)
>
> -Mitch
>
verify_area is gone in 2.1.x. Now, it is handled as a segfault within
the kernel -- no access, no trap, no EFAULT.
-hpa
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