Commit 49d925ce authored by Prasad J Pandit's avatar Prasad J Pandit Committed by Gerd Hoffmann
Browse files

usb: check page select value while processing iTD 



While processing isochronous transfer descriptors(iTD), the page
select(PG) field value could lead to an OOB read access. Add
check to avoid it.

Reported-by: default avatarQinghao Tang <luodalongde@gmail.com>
Signed-off-by: default avatarPrasad J Pandit <pjp@fedoraproject.org>
Message-id: 1453233406-12165-1-git-send-email-ppandit@redhat.com
Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent 10ae9d76

hw/usb/hcd-ehci.c

+6 −4
Original line number Diff line number Diff line
@@ -1405,21 +1405,23 @@ static int ehci_process_itd(EHCIState *ehci, 
        if (itd->transact[i] & ITD_XACT_ACTIVE) {

            pg   = get_field(itd->transact[i], ITD_XACT_PGSEL);

            off  = itd->transact[i] & ITD_XACT_OFFSET_MASK;

            ptr1 = (itd->bufptr[pg] & ITD_BUFPTR_MASK);

            ptr2 = (itd->bufptr[pg+1] & ITD_BUFPTR_MASK);

            len  = get_field(itd->transact[i], ITD_XACT_LENGTH);



            if (len > max * mult) {

                len = max * mult;

            }



            if (len > BUFF_SIZE) {

            if (len > BUFF_SIZE || pg > 6) {

                return -1;

            }



            ptr1 = (itd->bufptr[pg] & ITD_BUFPTR_MASK);

            qemu_sglist_init(&ehci->isgl, ehci->device, 2, ehci->as);

            if (off + len > 4096) {

                /* transfer crosses page border */

                if (pg == 6) {

                    return -1;  /* avoid page pg + 1 */

                }

                ptr2 = (itd->bufptr[pg + 1] & ITD_BUFPTR_MASK);

                uint32_t len2 = off + len - 4096;

                uint32_t len1 = len - len2;

                qemu_sglist_add(&ehci->isgl, ptr1 + off, len1);