[PATCH v2 1/4] HID: i2c-hid: fix memory corruption due to missing hid declaration

Benjamin Tissoires
2012-12-05T14:02:53Z

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>
---
drivers/hid/i2c-hid/i2c-hid.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index 7062df2..34cca42 100644
--- 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;
--
1.8.0.1