Date: Tue, 26 Nov 2013 17:03:23 +0000 From: Xen.org security team <security@....org> To: xen-announce@...ts.xen.org, xen-devel@...ts.xen.org, xen-users@...ts.xen.org, oss-security@...ts.openwall.com CC: Xen.org security team <security@....org> Subject: Xen Security Advisory 74 (CVE-2013-4553) - Lock order reversal between page_alloc_lock and mm_rwlock -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory CVE-2013-4553 / XSA-74 version 3 Lock order reversal between page_alloc_lock and mm_rwlock UPDATES IN VERSION 3 ==================== Public release. ISSUE DESCRIPTION ================= 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. IMPACT ====== A malicious guest administrator may be able to deny service to the entire host. VULNERABLE SYSTEMS ================== 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. MITIGATION ========== 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. CREDITS ======= This issue was discovered by Coverity Scan and diagnosed by Andrew Cooper. RESOLUTION ========== 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 0f7d0bbfbd7f3f1b6f6005321fa45081524dad438587f691e6892cc393327f89 xsa74-4.1-4.2.patch b505cdba662b1b1cd91d5611fac998c6b4e89e366780c6b9864b6965075afb38 xsa74-4.3-unstable.patch $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEbBAEBAgAGBQJSlNQrAAoJEIP+FMlX6CvZ0mQH91vaeR1HM9utM5SJqnVMVp9T lUsZRRsrI95Dh7dDaNl9IJC0vCWlIbdA4zMaSblYQtTkS8d6zx6psi9udjgkHGPj ZzKuJHN+qccXzphGe/pyIoA/Lpxk4at/JmNXzbXBonf1IOs6S9rVRkofyNswSWZC 2y8rKSrhXDMqrRKw42VEVWnmhiY8oV9Bez/+N0fEL1rhH8TxJYiQVGTlryquR6ye 1kvBsVYRQtYzjAWqj51wjFdeJnK9/l1W1jYDgPEZbe4fWUlhF1IlRLJVm+e9VpJd CdWGG4oBpVcXGig0mYFJ3Bmw5gmOi9zseXEDXbo7b0Xfw1tOIGujaHKN6eFj7A== =B5QR -----END PGP SIGNATURE----- Download attachment "xsa74-4.1-4.2.patch" of type "application/octet-stream" (1499 bytes) Download attachment "xsa74-4.3-unstable.patch" of type "application/octet-stream" (1389 bytes)
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