[PATCH 3.16 221/370] i2c: fix kernel memory disclosure in dev interface

[Ben Hutchings]

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

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

From: Vlad Tsyrklevich <vlad@xxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 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
@@ -334,7 +334,7 @@ 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,