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On Fri, Jul 06, 2007 at 12:57:53PM +0530, Bhanu Kalyan Chetlapalli wrote:
> On 7/6/07, hari krishna angadi <[EMAIL PROTECTED]> wrote:
> >hi all,
> >         In driver module i am using copy_to_user.i
> >have a user module,ths user module i pushed to hernel
> >and mafe as a driver module however copy_to_user works
> >but if i use memcpy() will be better ? whether memcpy
> >is efficient ?
> 
> copy_to_user is used in lieu of memcpy, only if the destination
> address/location is provided by the user. This is necessary to
> overcome attempts by malicious users to overwrite parts of the kernel
> or other places where they typically do not have access to. Another
> advantage is that the user space buffer might have been paged out, and
> so must be retrieved back into the RAM.

Or for architectures that don't have user space memory mapped into the
kernel VM (think x86 with 4G/4G memory split).


Erik

- -- 
They're all fools. Don't worry. Darwin may be slow, but he'll
eventually get them. -- Matthew Lammers in alt.sysadmin.recovery
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