From 351d6204bfc814a1aee300296d2f54460ffff172 Mon Sep 17 00:00:00 2001
From: Qixue Xiao <s2exqx@gmail.com>
Date: Fri, 20 Dec 2013 17:51:12 +0800
Subject: tty: an overflow of multiplication in drivers/tty/cyclades.c

there is an overflow in the code :
cyz_polling_cycle = (arg * HZ) / 1000,
the multiplicator arg comes from user, so it may be an overflow if
arg is a big number. And the value of cyc_polling_cycle will be
wrong when it is used next time.

Reported-by: Qixue Xiao <xiaoqixue_1@163.com>
Suggested-by: Yongjian Xu <xuyongjiande@gmail.com>
Suggested-by: Yu Chen <chyyuu@gmail.com>
Signed-off-by: Qixue Xiao <xiaoqixue_1@163.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/cyclades.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'drivers/tty/cyclades.c')

diff --git a/drivers/tty/cyclades.c b/drivers/tty/cyclades.c
index 33f83fee9fae..a57bb5ab761c 100644
--- a/drivers/tty/cyclades.c
+++ b/drivers/tty/cyclades.c
@@ -2709,6 +2709,8 @@ cy_ioctl(struct tty_struct *tty,
 		break;
 #ifndef CONFIG_CYZ_INTR
 	case CYZSETPOLLCYCLE:
+		if (arg > LONG_MAX / HZ)
+			return -ENODEV;
 		cyz_polling_cycle = (arg * HZ) / 1000;
 		break;
 	case CYZGETPOLLCYCLE:
-- 
cgit v1.2.3