regset: Return -EFAULT, not -EIO, on host-side memory fault

There is only one error code to return for a bad user-space buffer
pointer passed to a system call in the same address space as the
system call is executed, and that is EFAULT.  Furthermore, the
low-level access routines, which catch most of the faults, return
EFAULT already.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Roland McGrath <roland@hack.frob.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/regset.h

@@ -339,7 +339,7 @@ static inline int copy_regset_to_user(struct task_struct *target,
 		return -EOPNOTSUPP;
 
 	if (!access_ok(VERIFY_WRITE, data, size))
-		return -EIO;
+		return -EFAULT;
 
 	return regset->get(target, regset, offset, size, NULL, data);
 }
@@ -365,7 +365,7 @@ static inline int copy_regset_from_user(struct task_struct *target,
 		return -EOPNOTSUPP;
 
 	if (!access_ok(VERIFY_READ, data, size))
-		return -EIO;
+		return -EFAULT;
 
 	return regset->set(target, regset, offset, size, NULL, data);
 }