Commit message: usb: check RNDIS buffer offsets & length

When processing remote NDIS control message packets,
the USB Net device emulator uses a fixed length(4096) data buffer.
The incoming informationBufferOffset & Length combination could
overflow and cross that range. Check control message buffer
offsets and length to avoid it.

Reported-by: Qinghao Tang <luodalongde@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 1455648821-17340-3-git-send-email-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
CVE: CVE-2016-2538
CWE: CWE-189
Vulnerability description: Multiple integer overflows in the USB Net device emulator (hw/usb/dev-network.c) in QEMU before 2.5.1 allow local guest OS administrators to cause a denial of service (QEMU process crash) or obtain sensitive host memory information via a remote NDIS control message packet that is mishandled in the (1) rndis_query_response, (2) rndis_set_response, or (3) usb_net_handle_dataout function.

Project: qemu

static int rndis_query_response(USBNetState *s,
                rndis_query_msg_type *buf, unsigned int length)
{
    rndis_query_cmplt_type *resp;
    /* oid_supported_list is the largest data reply */
    uint8_t infobuf[sizeof(oid_supported_list)];
    uint32_t bufoffs, buflen;
    int infobuflen;
    unsigned int resplen;
 
     bufoffs = le32_to_cpu(buf->InformationBufferOffset) + 8;
     buflen = le32_to_cpu(buf->InformationBufferLength);
    if (bufoffs + buflen > length)
         return USB_RET_STALL;
 
     infobuflen = ndis_query(s, le32_to_cpu(buf->OID),
                             bufoffs + (uint8_t *) buf, buflen, infobuf,
    resplen = sizeof(rndis_query_cmplt_type) +
            ((infobuflen < 0) ? 0 : infobuflen);
    resp = rndis_queue_response(s, resplen);
    if (!resp)
        return USB_RET_STALL;

    resp->MessageType = cpu_to_le32(RNDIS_QUERY_CMPLT);
    resp->RequestID = buf->RequestID; /* Still LE in msg buffer */
    resp->MessageLength = cpu_to_le32(resplen);

    if (infobuflen < 0) {
        /* OID not supported */
        resp->Status = cpu_to_le32(RNDIS_STATUS_NOT_SUPPORTED);
        resp->InformationBufferLength = cpu_to_le32(0);
        resp->InformationBufferOffset = cpu_to_le32(0);
        return 0;
    }

    resp->Status = cpu_to_le32(RNDIS_STATUS_SUCCESS);
    resp->InformationBufferOffset =
            cpu_to_le32(infobuflen ? sizeof(rndis_query_cmplt_type) - 8 : 0);
    resp->InformationBufferLength = cpu_to_le32(infobuflen);
    memcpy(resp + 1, infobuf, infobuflen);

    return 0;
}

Project: qemu

static int rndis_set_response(USBNetState *s,
                rndis_set_msg_type *buf, unsigned int length)
{
    rndis_set_cmplt_type *resp =
            rndis_queue_response(s, sizeof(rndis_set_cmplt_type));
    uint32_t bufoffs, buflen;
    int ret;

    if (!resp)
        return USB_RET_STALL;

 
     bufoffs = le32_to_cpu(buf->InformationBufferOffset) + 8;
     buflen = le32_to_cpu(buf->InformationBufferLength);
    if (bufoffs + buflen > length)
         return USB_RET_STALL;
 
     ret = ndis_set(s, le32_to_cpu(buf->OID),
                     bufoffs + (uint8_t *) buf, buflen);
    resp->MessageLength = cpu_to_le32(sizeof(rndis_set_cmplt_type));
    if (ret < 0) {
        /* OID not supported */
        resp->Status = cpu_to_le32(RNDIS_STATUS_NOT_SUPPORTED);
        return 0;
    }
    resp->Status = cpu_to_le32(RNDIS_STATUS_SUCCESS);

    return 0;
}