Date: Thu, 12 Oct 2017 12:16:24 +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-team-members@....org> Subject: Xen Security Advisory 238 - DMOP map/unmap missing argument checks -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Xen Security Advisory XSA-238 version 2 DMOP map/unmap missing argument checks UPDATES IN VERSION 2 ==================== Public release. ISSUE DESCRIPTION ================= DMOPs (which were a subgroup of HVMOPs in older releases) allow guests to control and drive other guests. The I/O request server page mapping interface uses range sets to represent I/O resources the emulation of which is provided by a given I/O request server. The internals of the range set implementation require that ranges have a starting value no lower than the ending one. Checks for this fact were missing. IMPACT ====== Malicious or buggy stub domain kernels or tool stacks otherwise living outside of Domain0 can mount a denial of service attack which, if successful, can affect the whole system. Only domains controlling HVM guests can exploit this vulnerability. (This includes domains providing hardware emulation services to HVM guests.) VULNERABLE SYSTEMS ================== Xen versions 4.5 and later are vulnerable. Xen versions 4.4 and earlier are not vulnerable. Only x86 systems are affected. ARM systems are not affected. This vulnerability is only applicable to Xen systems using stub domains or other forms of disaggregation of control domains for HVM guests. MITIGATION ========== Running only PV guests will avoid this issue. (The security of a Xen system using stub domains is still better than with a qemu-dm running as an unrestricted dom0 process. Therefore users with these configurations should not switch to an unrestricted dom0 qemu-dm.) CREDITS ======= This issue was discovered by Vitaly Kuznetsov of RedHat. RESOLUTION ========== Applying the appropriate attached patch resolves this issue. xsa238.patch xen-unstable, Xen 4.9.x, Xen 4.8.x, Xen 4.7.x xsa238-4.6.patch Xen 4.6.x xsa238-4.5.patch Xen 4.5.x $ sha256sum xsa238* 3cced09a1fb2936644d654c568f38580952328b84e28601b019ea74122228c36 xsa238.meta 85d3f9713bef1bc86c682857dbd7388a1d1f20089363ddfc4cb9ecbd88eaffec xsa238.patch 034e91c234f6831dbaa1aaf29f4f90de2e822f99301424f7f3527f9da883ff68 xsa238-4.5.patch 29255a81729b24866e594426167de5fbef70de21ef62a95ba95de191d2a7fd54 xsa238-4.6.patch $ 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 administrators. 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 Team. (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: http://www.xenproject.org/security-policy.html -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBCAAGBQJZ31v7AAoJEIP+FMlX6CvZrBgIAMg3C1Gvc3rnrPjT+0Im7gdQ vBXGAWViWDs7EC1Vl5IU6lQQKETNmx40kRPyOYOVSdPzWamOotXOSadpJ49mbTX1 CA2iSJ8OAdqcPhgKjdUYVJXkybujNp6WkdlcT6ZXvEs6DLuvKJXZBaRoX2vYtObq JjwUfGgpHcOc8vLhaEjEZTWRnKJotqQPaPaDHzrtGJAkHB0F+gwqpM4lBD6Q18+/ DzyBWlDENEcoSwzDldZ/4Ktl/rOXDOPoYYZfnFmYA2puWP7ujonio8iofOy+6GH3 GoKSPs1ciC4ax1WdJqbuxM0TCStz4QFOselVQ0hEJNdH6k3mmA4wMg+6kPNDf2U= =9idj -----END PGP SIGNATURE----- Download attachment "xsa238.meta" of type "application/octet-stream" (1867 bytes) Download attachment "xsa238.patch" of type "application/octet-stream" (1545 bytes) Download attachment "xsa238-4.5.patch" of type "application/octet-stream" (1435 bytes) Download attachment "xsa238-4.6.patch" of type "application/octet-stream" (1435 bytes)
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