|Public release ||2013-11-26 12:00|
|Updated ||2013-11-26 17:02|
|Title ||Lock order reversal between page_alloc_lock and mm_rwlock|
Filesadvisory-74.txt (signed advisory file)
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Xen Security Advisory CVE-2013-4553 / XSA-74
Lock order reversal between page_alloc_lock and mm_rwlock
UPDATES IN VERSION 3
The locks page_alloc_lock and mm_rwlock are not always taken in
the same order. This raises the possibility of deadlock.
The incorrect order occurs only in the implementation of the
deprecated domctl hypercall XEN_DOMCTL_getmemlist.
A malicious guest administrator may be able to deny service to the
Xen 3.4.x and later are vulnerable.
Xen 3.3.x and earlier are not vulnerable.
Only systems where a privileged domain frequently or predictably uses
XEN_DOMCTL_getmemlist are vulnerable. (Its use by manually invoked
debugging and stress testing tools is not a security problem.)
We are not aware of any toolstack software which has relevant (and
hence vulnerable) uses of this hypercall. xend, libxl, xapi and
libvirt are known not to do so.
We are therefore not aware of any deployed Xen-based systems which are
vulnerable. We are issuing this advisory primarily for the benefit of
any Xen-derived systems using unusual toolstack software.
If you are using a toolstack (or other software) which uses
XEN_DOMCTL_getmemlist, disabling the relevant feature or functions may
be possible, and would avoid the vulnerability.
This issue was discovered by Coverity Scan and diagnosed by Andrew
Applying the appropriate attached patch resolves this issue.
xsa74-4.3-unstable.patch Xen 4.3.x, xen-unstable
xsa74-4.1-4.2.patch Xen 4.1.x, Xen 4.2.x
$ sha256sum xsa74*.patch
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Xenproject.org Security Team