char: Int overflow in lp_do_ioctl().

arg comes from user-space, so int overflow may occur:
	LP_TIME(minor) = arg * HZ/100;
Reported-by: Yongjian Xu <xuyongjiande@gmail.com>
Suggested-by: Qixue Xiao <s2exqx@gmail.com>
Signed-off-by: Yu Chen <chyyuu@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/lp.c

@@ -587,6 +587,8 @@ static int lp_do_ioctl(unsigned int minor, unsigned int cmd,
 		return -ENODEV;
 	switch ( cmd ) {
 		case LPTIME:
+			if (arg > UINT_MAX / HZ)
+				return -EINVAL;
 			LP_TIME(minor) = arg * HZ/100;
 			break;
 		case LPCHAR: