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From 49d925ce50383a286278143c05511d30ec41a36e Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
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 <luodalongde@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 1453233406-12165-1-git-send-email-ppandit@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
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 ab00268..93601d9 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -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);
--
2.7.4
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