linux-kernel - [PATCH 3.2 07/79] media: rc: check for integer overflow

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Date:   Sun, 11 Feb 2018 04:20:06 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Sean Young" <sean@...s.org>,
        "Mauro Carvalho Chehab" <mchehab@...pensource.com>
Subject: [PATCH 3.2 07/79] media: rc: check for integer overflow

3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Sean Young <sean@...s.org>

commit 3e45067f94bbd61dec0619b1c32744eb0de480c8 upstream.

The ioctl LIRC_SET_REC_TIMEOUT would set a timeout of 704ns if called
with a timeout of 4294968us.

Signed-off-by: Sean Young <sean@...s.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
[bwh: Backported to 3.2: open-code U32_MAX]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/media/rc/ir-lirc-codec.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/drivers/media/rc/ir-lirc-codec.c
+++ b/drivers/media/rc/ir-lirc-codec.c
@@ -255,11 +255,14 @@ static long ir_lirc_ioctl(struct file *f
 		if (!dev->max_timeout)
 			return -ENOSYS;
 
+		/* Check for multiply overflow */
+		if (val > (u32)(-1) / 1000)
+			return -EINVAL;
+
 		tmp = val * 1000;
 
-		if (tmp < dev->min_timeout ||
-		    tmp > dev->max_timeout)
-				return -EINVAL;
+		if (tmp < dev->min_timeout || tmp > dev->max_timeout)
+			return -EINVAL;
 
 		dev->timeout = tmp;
 		break;