Date: Wed, 12 Feb 2014 14:40:52 +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 88 - use-after-free in xc_cpupool_getinfo() under memory pressure -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory XSA-88 version 2 use-after-free in xc_cpupool_getinfo() under memory pressure UPDATES IN VERSION 2 ==================== Public release. ISSUE DESCRIPTION ================= If xc_cpumap_alloc() fails then xc_cpupool_getinfo() will free and incorrectly return the then-free pointer to the result structure. IMPACT ====== An attacker may be able to cause a multi-threaded toolstack using this function to race against itself leading to heap corruption and a potential DoS. Depending on the malloc implementation, privilege escalation cannot be ruled out. VULNERABLE SYSTEMS ================== The flaw is present in Xen 4.1 onwards. Only multithreaded toolstacks are vulnerable. Only systems where management functions (such as domain creation) are exposed to untrusted users are vulnerable. xl is not multithreaded, so is not vulnerable. However, multithreaded toolstacks using libxl as a library are vulnerable. xend is vulnerable. MITIGATION ========== Not allowing untrusted users access to toolstack functionality will avoid this issue. CREDITS ======= This issue was discovered by Coverity Scan and diagnosed by Andrew Cooper. RESOLUTION ========== Applying the attached patch resolves this issue. xsa88.patch xen-unstable, Xen 4.3.x, Xen 4.2.x, Xen 4.1.x $ sha256sum xsa88*.patch 7a73ca9db19a9ffe6e8cd259fa71dc1299738f26fa024303f4ab38931db75f14 xsa88.patch $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEcBAEBAgAGBQJS+4fOAAoJEIP+FMlX6CvZfUUH/2wyYKHOkEaEmcjUbuyUM3CT 8V9VgW4dhq/sk9p5SqR0xGB6N+f2XytCAFXI3kNmYjrs+jGK5cQgLjxMOwMKrpwm PsHCAZnGNzYMy48JtEUieEfwZqH/jNci7qJWNVdPoKnULOEd9X0hTri7vg1CoDI2 DUBeLvmC5mCFBej4pcDGX++XsdL90EnGa0RfrrVfIVf16EfBjgr8KzLKXd1uBueC yWKg5z24+HoRqFp3n3+Q9T6GN+npOj/78mrlXJ7onKepONAmLqg0J6g/1hHuc4hY pwUnbSf0452FKTFs7KUodXoJNNX1i3IuOch9pBcKlrbT6K/g/qwMZ/Pl2Ir8a20= =vA6e -----END PGP SIGNATURE----- [ CONTENT OF TYPE application/octet-stream SKIPPED ]
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