File 0207-vmw_pvscsi-check-message-ring-page-.patch of Package qemu.12243

From 0c8f4b44b5cf0121805f61cc8f4f6e0c9ba5688d Mon Sep 17 00:00:00 2001
From: P J P <ppandit@redhat.com>
Date: Tue, 25 Apr 2017 07:07:00 -0600
Subject: [PATCH] vmw_pvscsi: check message ring page count at initialisation

Vmware Paravirtual SCSI emulation uses command descriptors to
process SCSI commands. These come with their message ring buffers.
A guest could set the message ring page count to an arbitrary value
resulting in infinite loop. Add check to avoid it.

Reported-by: YY Z <bigbird475958471@gmail.com>
Signed-off-by: P J P <ppandit@redhat.com>
(cherry picked from commit f68826989cd4d1217797251339579c57b3c0934e)
[BR: BSC#1036211 CVE-2017-8112]
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 hw/scsi/vmw_pvscsi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/scsi/vmw_pvscsi.c b/hw/scsi/vmw_pvscsi.c
index a13e72c9db..3334d1b314 100644
--- a/hw/scsi/vmw_pvscsi.c
+++ b/hw/scsi/vmw_pvscsi.c
@@ -203,7 +203,7 @@ pvscsi_ring_init_msg(PVSCSIRingInfo *m, PVSCSICmdDescSetupMsgRing *ri)
     uint32_t len_log2;
     uint32_t ring_size;
 
-    if (ri->numPages > PVSCSI_SETUP_MSG_RING_MAX_NUM_PAGES) {
+    if (!ri->numPages || ri->numPages > PVSCSI_SETUP_MSG_RING_MAX_NUM_PAGES) {
         return -1;
     }
     ring_size = ri->numPages * PVSCSI_MAX_NUM_MSG_ENTRIES_PER_PAGE;