linux-kernel - [PATCH 4.4 24/48] i2c: fix kernel memory disclosure in dev interface

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Date:   Wed, 18 Jan 2017 11:46:33 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vlad Tsyrklevich <vlad@...rklevich.net>,
        Wolfram Sang <wsa@...-dreams.de>
Subject: [PATCH 4.4 24/48] i2c: fix kernel memory disclosure in dev interface

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Vlad Tsyrklevich <vlad@...rklevich.net>

commit 30f939feaeee23e21391cfc7b484f012eb189c3c upstream.

i2c_smbus_xfer() does not always fill an entire block, allowing
kernel stack memory disclosure through the temp variable. Clear
it before it's read to.

Signed-off-by: Vlad Tsyrklevich <vlad@...rklevich.net>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/i2c/i2c-dev.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -329,7 +329,7 @@ static noinline int i2cdev_ioctl_smbus(s
 		unsigned long arg)
 {
 	struct i2c_smbus_ioctl_data data_arg;
-	union i2c_smbus_data temp;
+	union i2c_smbus_data temp = {};
 	int datasize, res;
 
 	if (copy_from_user(&data_arg,