|Public release ||2017-02-23 16:28|
|Updated ||2017-02-23 16:28|
|CVE(s) ||none (yet) assigned|
|Title ||arm: memory corruption when freeing p2m pages|
Filesadvisory-210.txt (signed advisory file)
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Xen Security Advisory XSA-210
arm: memory corruption when freeing p2m pages
When freeing pages used for stage-2 page tables, the freeing routine
failed to remove these pages from an internally managed list they were
put on during allocation. The same list node elements are also
used by the hypervisor's page allocator. Subsequent manipulation of
ARM's private P2M list could therefore corrupt the lists maintained by
the page allocator. The buggy code is exposed to guests via the
A malicious or buggy guest may corrupt hypervisor state, commonly
leading to a host crash (Denial of Service). Privilege escalation or
information leaks cannot be excluded.
Only Xen version 4.8 is affected. Xen versions 4.7 and earlier are not
Only ARM systems are vulnerable. X86 based systems are not vulnerable.
There is no known mitigation.
NOTE REGARDING LACK OF EMBARGO
The issue was discussed publicly before being recognized as a security
Applying the attached patch resolves this issue.
xsa210.patch xen-unstable, Xen 4.8.x
$ sha256sum xsa210*
The initial bug was discovered by Vijay Kilari of Cavium and the
security aspect was diagnosed by Julien Grall of ARM.
DEPLOYMENT DURING EMBARGO
Deployment of the patches and/or mitigations described above (or
others which are substantially similar) is permitted during the
embargo, even on public-facing systems with untrusted guest users and
But: Distribution of updated software is prohibited (except to other
members of the predisclosure list).
Predisclosure list members who wish to deploy significantly different
patches and/or mitigations, please contact the Xen Project Security
(Note: this during-embargo deployment notice is retained in
post-embargo publicly released Xen Project advisories, even though it
is then no longer applicable. This is to enable the community to have
oversight of the Xen Project Security Team's decisionmaking.)
For more information about permissible uses of embargoed information,
consult the Xen Project community's agreed Security Policy:
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Xenproject.org Security Team