Missing NUMA node parameter verification

ISSUE DESCRIPTION The function allocheappages allows callers to specify the first NUMA node that should be used for allocations through the memflags parameter; the node is extracted using the MEMFgetnode macro. While the function checks to see if the special constant NUMANONODE is specified, it...

cxenstored: Race in domain cleanup

ISSUE DESCRIPTION When shutting down a VM with a stubdomain, a race in cxenstored may cause a double-free. IMPACT The xenstored daemon may crash, resulting in a DoS of any parts of the system relying on it including domain creation / destruction, ballooning, device changes, etc. VULNERABLE SYSTEM...

x86: PV privilege escalation via map_grant_ref

ISSUE DESCRIPTION When mapping a grant reference, a guest must inform Xen of where it would like the grant mapped. For PV guests, this is done by nominating an existing linear address, or an L1 pagetable entry, to be altered. Neither of these PV paths check for alignment of the passed parameter...

CVE-2017-10921

The grant-table feature in Xen through 4.8.x does not ensure sufficient type counts for a GNTMAPdevicemap and GNTMAPhostmap mapping, which allows guest OS users to cause a denial of service count mismanagement and memory corruption or obtain privileged host OS access, aka XSA-224 bug 2. Mitigatio...

CVE-2017-10918

Xen through 4.8.x does not validate memory allocations during certain P2M operations, which allows guest OS users to obtain privileged host OS access, aka XSA-222. Mitigation On x86, specifying "hap1gb=0 hap2mb=0" on the hypervisor command line will avoid the vulnerability. Alternatively, running...

stale P2M mappings due to insufficient error checking

ISSUE DESCRIPTION Certain actions require removing pages from a guest's P2M Physical-to-Machine mapping. When large pages are in use to map guest pages in the 2nd-stage page tables, such a removal operation may incur a memory allocation to replace a large mapping with individual smaller ones. If...

Races in the grant table unmap code

ISSUE DESCRIPTION We have discovered two bugs in the code unmapping grant references. When a grant had been mapped twice by a backend domain, and then unmapped by two concurrent unmap calls, the frontend may be informed that the page had no further mappings when the first call completed rather th...

x86: insufficient reference counts during shadow emulation

ISSUE DESCRIPTION When using shadow paging, writes to guest pagetables must be trapped and emulated, so the shadows can be suitably adjusted as well. When emulating the write, Xen maps the guests pagetables to make the final adjustment and leave the guest's view of its state consistent. However,...

page transfer may allow PV guest to elevate privilege

ISSUE DESCRIPTION Domains controlling other domains are permitted to map pages owned by the domain being controlled. If the controlling domain unmaps such a page without flushing the TLB, and if soon after the domain being controlled transfers this page to another PV domain via GNTTABOPtransfer o...

grant table operations mishandle reference counts

ISSUE DESCRIPTION We have discovered a number of bugs in the code mapping and unmapping grant references. If a grant is mapped with both the GNTMAPdevicemap and GNTMAPhostmap flags, but unmapped only with hostmap, the devicemap portion remains but the page reference counts are lowered as though i...

x86: PKRU and BND* leakage between vCPU-s

ISSUE DESCRIPTION Memory Protection Extensions MPX and Protection Key PKU are features in newer processors, whose state is intended to be per-thread and context switched along with all other XSAVE state. Xen's vCPU context switch code would save and restore the state only if the guest had set the...

x86: 64bit PV guest breakout via pagetable use-after-mode-change

ISSUE DESCRIPTION 64-bit PV guests typically use separate root page tables for their kernel and user modes. Hypercalls are accessible to guest kernel context only, which certain hypercall handlers make assumptions on. The IRET hypercall replacing the identically name CPU instruction is used by...

Xen: Privilege Escalation

Background Xen is a bare-metal hypervisor. Description In CIRRUSBLTMODEMEMSYSSRC mode the bitblit copy routine cirrusbitbltcputovideo fails to check wethehr the specified memory region is safe. Impact A local attacker could potentially execute arbitrary code with privileges of Xen QEMU process on...

Citrix XenServer Security Update for CVE-2016-9603 (CTX221578)

A security issue has been identified within Citrix XenServer. SPDX-FileCopyrightText: 2017 Greenbone AG Some text descriptions might be excerpted from a referenced sources, and are Copyright C by the respective right holders. SPDX-License-Identifier: GPL-2.0-only CPE = "cpe:/a:citrix:xenserver"; ...

Cirrus VGA Heap overflow via display refresh

ISSUE DESCRIPTION When a graphics update command gets passed to the VGA emulator, there are 3 possible modes that can be used to update the display: blank - Clears the display text - Treats the display as showing text graph - Treats the display as showing graphics After the display geometry gets...

CVE-2016-9603 - Citrix XenServer Security Update

Description of Problem A security issue has been identified within Citrix XenServer. This issue could, if exploited, allow the administrator of an HVM guest VM to compromise the host. The following vulnerability has been addressed: CVE-2016-9603 High: QEMU: Cirrus VGA Heap overflow via display...

CVE-2016-9377

Xen 4.5.x through 4.7.x on AMD systems without the NRip feature, when emulating instructions that generate software interrupts, allows local HVM guest OS users to cause a denial of service guest crash by leveraging IDT entry miscalculation...

ALPINE-CVE-2016-9378

Xen 4.5.x through 4.7.x on AMD systems without the NRip feature, when emulating instructions that generate software interrupts, allows local HVM guest OS users to cause a denial of service guest crash by leveraging an incorrect choice for software interrupt delivery...

UBUNTU-CVE-2016-9378

Xen 4.5.x through 4.7.x on AMD systems without the NRip feature, when emulating instructions that generate software interrupts, allows local HVM guest OS users to cause a denial of service guest crash by leveraging an incorrect choice for software interrupt delivery...

DEBIAN-CVE-2016-9377

Xen 4.5.x through 4.7.x on AMD systems without the NRip feature, when emulating instructions that generate software interrupts, allows local HVM guest OS users to cause a denial of service guest crash by leveraging IDT entry miscalculation...