Re: [PATCH 02/14] HID: i2c-hid: fix memory corruption due tomissing hid declaration

From: Jean Delvare
Date: Tue Dec 04 2012 - 16:42:04 EST


On Tue, 4 Dec 2012 16:27:43 +0100, Benjamin Tissoires wrote:
> 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@xxxxxxxxx>
> ---
> drivers/hid/i2c-hid/i2c-hid.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index 0fbb229..ad771a7 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -68,6 +68,7 @@ struct i2c_hid_desc {
> __le16 wVendorID;
> __le16 wProductID;
> __le16 wVersionID;
> + __le32 reserved;
> } __packed;
>
> struct i2c_hid_cmd {
> @@ -778,7 +779,7 @@ 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) {
> + if (!dsize || dsize > sizeof(struct i2c_hid_desc)) {

Shouldn't !dsize rather be dsize < 4? You're reading hdesc->bcdVersion,
which is only defined if dsize >= 4 if I understand the code correctly.

> dev_err(&client->dev, "weird size of HID descriptor (%u)\n",
> dsize);
> return -ENODEV;


--
Jean Delvare
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