linux-kernel - [PATCH] media: rc: ir-lirc-codec: fix potential integer overflow

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Message-Id: <1290791197-21403-1-git-send-email-segoon@openwall.com>
Date:	Fri, 26 Nov 2010 20:06:35 +0300
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	kernel-janitors@...r.kernel.org
Cc:	Mauro Carvalho Chehab <mchehab@...radead.org>,
	David Härdeman <david@...deman.nu>,
	Jarod Wilson <jarod@...hat.com>, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] media: rc: ir-lirc-codec: fix potential integer overflow

'n' may be bigger than MAX_INT*sizeof(int), if so checking of truncated
(int)(n/sizeof(int)) for LIRCBUF_SIZE overflow and then using nontruncated 'count'
doesn't make sense.  Also n may be up to sizeof(int)-1 bytes bigger than expected,
so check value of (n % sizeof(int)) too.

Signed-off-by: Vasiliy Kulikov <segoon@...nwall.com>
---
 Compile tested only.

 drivers/media/rc/ir-lirc-codec.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c
index 1e87ee8..f011c5d 100644
--- a/drivers/media/rc/ir-lirc-codec.c
+++ b/drivers/media/rc/ir-lirc-codec.c
@@ -100,7 +100,8 @@ static ssize_t ir_lirc_transmit_ir(struct file *file, const char *buf,
 	struct lirc_codec *lirc;
 	struct rc_dev *dev;
 	int *txbuf; /* buffer with values to transmit */
-	int ret = 0, count;
+	int ret = 0;
+	size_t count;
 
 	lirc = lirc_get_pdata(file);
 	if (!lirc)
@@ -110,7 +111,7 @@ static ssize_t ir_lirc_transmit_ir(struct file *file, const char *buf,
 		return -EINVAL;
 
 	count = n / sizeof(int);
-	if (count > LIRCBUF_SIZE || count % 2 == 0)
+	if (count > LIRCBUF_SIZE || count % 2 == 0 || n % sizeof(int) != 0)
 		return -EINVAL;
 
 	txbuf = memdup_user(buf, n);
-- 
1.7.0.4

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