fcntl: return -EFAULT if copy_to_user fails

copy_to_user() returns the number of bytes remaining, but we want to
return -EFAULT.
ret = fcntl(fd, F_SETOWN_EX, NULL);
With the original code ret would be 8 here.

V2: Takuya Yoshikawa pointed out a similar issue in f_getown_ex()

Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: Al Viro <[e-mail]>

fs/fcntl.c

···
 
 	ret = copy_from_user(&owner, owner_p, sizeof(owner));
 	if (ret)
-		return ret;
+		return -EFAULT;
 
 	switch (owner.type) {
 	case F_OWNER_TID:
···
 	}
 	read_unlock(&filp->f_owner.lock);
 
-	if (!ret)
+	if (!ret) {
 		ret = copy_to_user(owner_p, &owner, sizeof(owner));
+		if (ret)
+			ret = -EFAULT;
+	}
 	return ret;
 }