usb: gadget: rndis: Fix info leak of rndis

hulk inclusion
category: bugfix
bugzilla: 172330
CVE: NA

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

We can construct some special USB packets that cause kernel
info leak by the following steps of rndis.

1. construct the packet to make rndis call gen_ndis_set_resp().

In gen_ndis_set_resp(), BufOffset comes from the USB packet and
it is not checked so that BufOffset can be any value. Therefore,
if OID is RNDIS_OID_GEN_CURRENT_PACKET_FILTER, then *params->filter
can get data at any address.

2. construct the packet to make rndis call rndis_query_response().

In rndis_query_response(), if OID is RNDIS_OID_GEN_CURRENT_PACKET_FILTER,
then the data of *params->filter is fetched and returned, resulting in
info leak.

Therefore, we need to check the BufOffset to prevent info leak. Here,
buf size is USB_COMP_EP0_BUFSIZ, as long as "8 + BufOffset + BufLength"
is less than USB_COMP_EP0_BUFSIZ, it will be considered legal.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>