Bugzilla – Bug 1179504
VUL-0: CVE-2020-29485: xen: oxenstored memory leak in reset_watches (XSA-330 v3)
Last modified: 2020-12-15 13:13:26 UTC
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Xen Security Advisory CVE-2020-29485 / XSA-330
oxenstored memory leak in reset_watches
UPDATES IN VERSION 3
When acting upon a guest XS_RESET_WATCHES request, not all tracking
information is freed.
A guest can cause unbounded memory usage in oxenstored. This can lead
to a system-wide DoS.
All version of Xen since 4.6 are vulnerable.
Only systems using the Ocaml Xenstored implementation are vulnerable.
Systems using the C Xenstored implementaion are not vulnerable.
There are no mitigations.
Changing to use of C xenstored would avoid this vulnerability. However,
given the other vulnerabilities in both versions of xenstored being
reported at this time, changing xenstored implementation is not a
recommended approach to mitigation of individual issues.
This issue was discovered by Edwin Török of Citrix.
Applying the appropriate attached patch resolves this issue.
Note that patches for released versions are generally prepared to
apply to the stable branches, and may not apply cleanly to the most
recent release tarball. Downstreams are encouraged to update to the
tip of the stable branch before applying these patches.
xsa330.patch Xen 4.12 - xen-unstable
xsa330-4.11.patch Xen 4.10 - 4.11
$ sha256sum xsa330*
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is then no longer applicable.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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