[PATCH 3.18 26/32] HID: i2c-hid: allocate hid buffers for real worst case

[Greg Kroah-Hartman]

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

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

From: Adrian Salido <salidoa@xxxxxxxxxx>

commit 8320caeeffdefec3b58b9d4a7ed8e1079492fe7b upstream.

The buffer allocation is not currently accounting for an extra byte for
the report id. This can cause an out of bounds access in function
i2c_hid_set_or_send_report() with reportID > 15.

Signed-off-by: Adrian Salido <salidoa@xxxxxxxxxx>
Reviewed-by: Benson Leung <bleung@xxxxxxxxxxxx>
Signed-off-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/hid/i2c-hid/i2c-hid.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -526,7 +526,8 @@ static int i2c_hid_alloc_buffers(struct
 {
 	/* the worst case is computed from the set_report command with a
 	 * reportID > 15 and the maximum report length */
-	int args_len = sizeof(__u8) + /* optional ReportID byte */
+	int args_len = sizeof(__u8) + /* ReportID */
+		       sizeof(__u8) + /* optional ReportID byte */
 		       sizeof(__u16) + /* data register */
 		       sizeof(__u16) + /* size of the report */
 		       report_size; /* report */