Re: Question on verify_area() and friends wrt

[Christoph Hellwig <hch@infradead.org>]

On Sun, May 25, 2003 at 12:46:25PM +0100, Paulo Andre' wrote:
> if (!verify_area(VERIFY_WRITE, ptr, sizeof(ir) +
> 		(sizeof(struct inquiry_info) * ir.num_rsp))) {
>     copy_to_user(ptr, &ir, sizeof(ir));
>     ptr += sizeof(ir);
>     copy_to_user(ptr, buf, sizeof(struct inquiry_info) * ir.num_rsp);	} else
>     err = -EFAULT;
> 
> I'm presuming verify_area() does its job fine returning 0 if the memory
> is valid and -EFAULT if not. Thus, given the exact check that's been
> done, there seems indeed to exist no need to check each call to
> copy_to_user() below. Or is there?

verify_area only does some checks so you need to check the return value
from copy_to_user.  You could switch to __copy_to_user, though.