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From: xqx12 <s2exqx@gmail.com>
To: gregkh@linuxfoundation.org, jslaby@suse.cz
Cc: linux-kernel@vger.kernel.org, chyyuu@gmail.com,
	xuyongjiande@gmail.com, xqx12 <xiaoqixue_1@163.com>
Subject: [PATCH] tty: an overflow of multiplication in drivers/tty/cyclades.c
Date: Wed, 18 Dec 2013 09:00:29 +0800	[thread overview]
Message-ID: <1387328429-15172-1-git-send-email-xiaoqixue_1@163.com> (raw)

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>
---
 drivers/tty/cyclades.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/cyclades.c b/drivers/tty/cyclades.c
index 33f83fe..a57bb5a 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:
-- 
1.7.9.5


             reply	other threads:[~2013-12-18  1:00 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-18  1:00 xqx12 [this message]
2013-12-19  0:57 ` [PATCH] tty: an overflow of multiplication in drivers/tty/cyclades.c Greg KH
2013-12-19 10:12   ` xiaoqixue_1
  -- strict thread matches above, loose matches on Subject: below --
2013-12-20  9:49 Qixue Xiao
2013-12-16 14:21 xqx12
2013-12-17 17:39 ` Greg KH

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