fs/read_write.c:compat_readv(): remove bogus area verify

The compat_do_readv_writev() function was doing a verify_area on the
incoming iov, but the nr_segs value is not checked.  If someone passes
in a -1 for nr_segs, for instance, the function should return an EINVAL.
However, it returns a EFAULT because the verify_area fails because it is
checking an array of size MAX_UINT.  The check is bogus, anyway, because
the next check, compat_rw_copy_check_uvector(), will do all the
necessary checking, anyway.  The non-compat do_readv_writev() function
doesn't do this check, so I think it's safe to just remove the code.
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/read_write.c

@@ -901,10 +901,6 @@ static ssize_t compat_do_readv_writev(int type, struct file *file,
 	io_fn_t fn;
 	iov_fn_t fnv;
 
-	ret = -EFAULT;
-	if (!access_ok(VERIFY_READ, uvector, nr_segs*sizeof(*uvector)))
-		goto out;
-
 	ret = compat_rw_copy_check_uvector(type, uvector, nr_segs,
 					       UIO_FASTIOV, iovstack, &iov);
 	if (ret <= 0)