HID: i2c-hid: fix memory corruption due to missing hid declaration

HID descriptors contains 4 bytes of reserved field.
The previous implementation was overriding the next fields in struct i2c_hid.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index 7062df2..34cca42 100644 (file)
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -69,6 +69,7 @@ struct i2c_hid_desc {
        __le16 wVendorID;
        __le16 wProductID;
        __le16 wVersionID;
+       __le32 reserved;
 } __packed;
 
 struct i2c_hid_cmd {
@@ -776,7 +777,13 @@ static int __devinit i2c_hid_fetch_hid_descriptor(struct i2c_hid *ihid)
        }
 
        dsize = le16_to_cpu(hdesc->wHIDDescLength);
-       if (!dsize || dsize > HID_MAX_DESCRIPTOR_SIZE) {
+       /*
+        * the size of the HID descriptor should at least contain
+        * its size and the bcdVersion (4 bytes), and should not be greater
+        * than sizeof(struct i2c_hid_desc) as we directly fill this struct
+        * through i2c_hid_command.
+        */
+       if (dsize < 4 || dsize > sizeof(struct i2c_hid_desc)) {
                dev_err(&client->dev, "weird size of HID descriptor (%u)\n",
                        dsize);
                return -ENODEV;