From: Prasad J Pandit Date: Wed, 20 Jan 2016 01:26:46 +0530 Subject: [PATCH] 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: Qinghao Tang Signed-off-by: Prasad J Pandit Message-id: 1453233406-12165-1-git-send-email-ppandit@redhat.com Signed-off-by: Gerd Hoffmann (cherry picked from commit 49d925ce50383a286278143c05511d30ec41a36e) --- hw/usb/hcd-ehci.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c index d07f228..c40013e 100644 --- a/hw/usb/hcd-ehci.c +++ b/hw/usb/hcd-ehci.c @@ -1404,21 +1404,23 @@ 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);