usb: ccid: check ccid apdu length

CCID device emulator uses Application Protocol Data Units(APDU)
to exchange command and responses to and from the host.
The length in these units couldn't be greater than 65536. Add
check to ensure the same. It'd also avoid potential integer
overflow in emulated_apdu_from_guest.

Reported-by: Li Qiang <liqiang6-s@360.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 20170202192228.10847-1-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

diff --git a/hw/usb/dev-smartcard-reader.c b/hw/usb/dev-smartcard-reader.c
index 89e11b6..1325ea1 100644 (file)
--- a/hw/usb/dev-smartcard-reader.c
+++ b/hw/usb/dev-smartcard-reader.c
@@ -967,7 +967,7 @@ static void ccid_on_apdu_from_guest(USBCCIDState *s, CCID_XferBlock *recv)
     DPRINTF(s, 1, "%s: seq %d, len %d\n", __func__,
                 recv->hdr.bSeq, len);
     ccid_add_pending_answer(s, (CCID_Header *)recv);
-    if (s->card) {
+    if (s->card && len <= BULK_OUT_DATA_SIZE) {
         ccid_card_apdu_from_guest(s->card, recv->abData, len);
     } else {
         DPRINTF(s, D_WARN, "warning: discarded apdu\n");