x86: Incorrect handling of self-linear shadow mappings with translated guests

ISSUE DESCRIPTION The shadow pagetable code uses linear mappings to inspect and modify the shadow pagetables. A linear mapping which points back to itself is known as self-linear. For translated guests, the shadow linear mappings being in a separate address space are not intended to be self-linea...

x86: Incorrect handling of IST settings during CPU hotplug

ISSUE DESCRIPTION The x86-64 architecture allows interrupts to be run on distinct stacks. The choice of stack is encoded in a field of the corresponding interrupt descriptor in the Interrupt Descriptor Table IDT. That field selects an entry from the active Task State Segment TSS. Since, on AMD...

Unlimited recursion in linear pagetable de-typing

ISSUE DESCRIPTION x86 PV guests are permitted to set up certain forms of what is often called "linear page tables", where pagetables contain references to other pagetables at the same level or higher. Certain restrictions apply in order to fit into Xen's page type handling system. An important...

hypervisor stack leak in x86 I/O intercept code

ISSUE DESCRIPTION Intercepted I/O operations may deal with less than a full machine word's worth of data. While read paths had been the subject of earlier XSAs and hence have been fixed, at least one write path was found where the data stored into an internal structure could contain bits from an...

Security update for xen (important)

This update for xen fixes several issues. These security issues were fixed: - CVE-2017-14316: Missing bound check in function allocheappages for an internal array allowed attackers using crafted hypercalls to execute arbitrary code within Xen XSA-231, bsc1056278 - CVE-2017-14318: The function...

SUSE-SU-2017:2420-1 Security update for xen

This update for xen fixes several issues. These security issues were fixed: - CVE-2017-14316: Missing bound check in function allocheappages for an internal array allowed attackers using crafted hypercalls to execute arbitrary code within Xen XSA-231, bsc1056278 - CVE-2017-14318: The function...

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...

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...

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...

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: 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,...

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...

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...

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"; ...