From: Qixue Xiao <s2exqx@gmail.com>
Date: Fri, 20 Dec 2013 09:51:12 +0000 (+0800)
Subject: tty: an overflow of multiplication in drivers/tty/cyclades.c
X-Git-Tag: firefly_0821_release~176^2~4543^2~15
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=351d6204bfc814a1aee300296d2f54460ffff172;p=firefly-linux-kernel-4.4.55.git

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>
---

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: