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Xen Security Advisory CVE-2017-7228 / XSA-212
x86: broken check in memory_exchange() permits PV guest breakout
UPDATES IN VERSION 3
The XSA-29 fix introduced an insufficient check on XENMEM_exchange
input, allowing the caller to drive hypervisor memory accesses outside
of the guest provided input/output arrays.
A malicious or buggy 64-bit PV guest may be able to access all of
system memory, allowing for all of privilege escalation, host crashes,
and information leaks.
All Xen versions are vulnerable.
Only x86 systems are affected. ARM systems are not vulnerable.
The vulnerability is only exposed to 64-bit PV guests. HVM guests and
32-bit PV guests can't exploit the vulnerability.
Running only HVM or 32-bit PV guests will avoid the vulnerability.
The vulnerability can be avoided if the guest kernel is controlled by
the host rather than guest administrator, provided that further steps
are taken to prevent the guest administrator from loading code into
the kernel (e.g. by disabling loadable modules etc) or from using
other mechanisms which allow them to run code at kernel privilege.
This issue was discovered by Jann Horn of Google Project Zero.
Applying the attached patch resolves this issue.
xsa212.patch xen-unstable, Xen 4.8.x, Xen 4.7.x, Xen 4.6.x, Xen 4.5.x, Xen 4.4.x
according to https://www.xenproject.org/downloads/xen-archives/xen-project-48-series/xen-481.html
XSA-212 patch is applied in 4.8.1 release.
(In reply to Oleg from comment #1)
yes, this should be already fixed at
Oleg thank you for bringing it to our attention.
Since our X86 version is not available (not keyword) this bug does not apply I am closing this bug and changing the whiteboard.