Date: Mon, 06 Jun 2016 14:26:14 +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 181 (CVE-2016-5242) - arm: Host crash caused by VMID exhaustion -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory CVE-2016-5242 / XSA-181 version 2 arm: Host crash caused by VMID exhaustion UPDATES IN VERSION 2 ==================== CVE assigned. ISSUE DESCRIPTION ================= VMIDs are a finite hardware resource, and allocated as part of domain creation. If no free VMIDs are available when trying to create a new domain, a bug in the error path causes a NULL pointer to be used, resulting in a Data Abort and host crash. IMPACT ====== Attempting to create too many concurrent domains causes a host crash rather than a graceful error. A malicious device driver domain can hold references to domains, preventing its VMID being released. VULNERABLE SYSTEMS ================== Xen versions 4.4 and later are affected. Older Xen versions are unaffected. x86 systems are not affected. Only arm systems with less-privileged device driver domains can expose this vulnerability. MITIGATION ========== There is no mitigation. Not using driver domains reclassifies the problem, but does not fix it. NOTE REGARDING LACK OF EMBARGO ============================== The crash was discussed publicly on xen-devel, before it was appreciated that there was a security problem. CREDITS ======= This issue was discovered by Aaron Cornelius of DornerWorks. RESOLUTION ========== Applying the appropriate attached patch resolves this issue. xsa181.patch xen-unstable, Xen 4.6.x, 4.5.x xsa181-4.4.patch Xen 4.4.x $ sha256sum xsa181* 6756fcf44446675e5277f6d6c0e8a0aaa51a7909ad9a55af89a09367fded8733 xsa181.patch 97a90c7cb42466647622cb2ed98de531b7ba2e174a1bc639a32a6f1b626d503f xsa181-4.4.patch $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEbBAEBAgAGBQJXUYxcAAoJEIP+FMlX6CvZgAAH+OiNDLSkAHUl3isXjFzK+Mf9 NGuIyXc2j5K8uTwz5KvZkhiWLVCeOY7Jo1Wix3Fa1wFtJ2rMlgQf7/hOt0tk0NjU w97Re+xSi69iruPEdwb4k31ohnlfLSqriqL4JWh6EDrhftdnvEk/yXmriyu1RhKy MLk1P24Ora/gvSj31px3vBkbu8KLImhIOkOcRmJ7FQb8gWsmMDluuVu7lhUAL7im KCe6u99sDQo18wxubYID4XxFqJExBUd6L3cnpdN4UITgylSaIqJq/RBwd8jRrxW8 MxT9/IcNf0rmB1Sh1IARBFF7P7hj76ho3sIpMeE0cMPWBe2NWMItX9ula61vQA== =kBFB -----END PGP SIGNATURE----- Download attachment "xsa181.patch" of type "application/octet-stream" (1243 bytes) Download attachment "xsa181-4.4.patch" of type "application/octet-stream" (1285 bytes)
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