Date: Thu, 04 Mar 2021 10:39:44 +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 367 v1 - Linux: netback fails to honor grant mapping errors -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Xen Security Advisory XSA-367 Linux: netback fails to honor grant mapping errors ISSUE DESCRIPTION ================= XSA-362 tried to address issues here, but in the case of the netback driver the changes were insufficient: It left the relevant function invocation with, effectively, no error handling at all. As a result, memory allocation failures there could still lead to frontend-induced crashes of the backend. IMPACT ====== A malicious or buggy networking frontend driver may be able to crash the corresponding backend driver, potentially affecting the entire domain running the backend driver. In a typical (non-disaggregated) system that is a host-wide denial of service (DoS). VULNERABLE SYSTEMS ================== Linux versions from at least 2.6.39 onwards are vulnerable, when run in PV mode. Earlier versions differ significantly in behavior and may therefore instead surface other issues under the same conditions. Linux run in HVM / PVH modes is not vulnerable. MITIGATION ========== For Linux, running the backends in HVM or PVH domains will avoid the vulnerability. For example, by running the dom0 in PVH mode. In all other cases there is no known mitigation. RESOLUTION ========== Applying the attached patch resolves this issue. xsa367-linux.patch Linux 5.12-rc $ sha256sum xsa367* b0244bfddee91cd7986172893e70664b74e698c5d44f25865870f179f80f9a92 xsa367-linux.patch $ CREDITS ======= This issue was reported by Intel's kernel test robot and recognized as a security issue by Jan Beulich of SUSE. NOTE REGARDING LACK OF EMBARGO ============================== This issue was reported publicly, before the XSA could be issued. -----BEGIN PGP SIGNATURE----- iQFABAEBCAAqFiEEI+MiLBRfRHX6gGCng/4UyVfoK9kFAmBAuOYMHHBncEB4ZW4u b3JnAAoJEIP+FMlX6CvZUCAH/1zw5d2l1R3k+nvJ659plwOYDe8Cmh4GeJ02PoUv fC/5efe7l/tXEmfg4rg5WiY8JZqQGeGmhwiOs8bI/8c5IXucaPOM1wDUaHUMkWTA tl/P/tbDamzd1/dSK4DdILTApibU+M/nmUn0sBBYpu53VUbeyXq2EAtjmliKgCG9 Oo4PW4ys5ro+hwrPtYdLD1ktIN64+C+TqkKUdJset7po5sWX4nV1Cwp/4oKaNyeF Alh495TUCnhgc8gnXUgXhmxWKp3Iag/tHjmtu34mT5HHZdBrNBShFKhHSP5bJHE2 CxYD1b/KbkRiLPOgZXNec+ikDQT4bTCeVLpnWvOXQ1FTXR4= =hY2s -----END PGP SIGNATURE----- Download attachment "xsa367-linux.patch" of type "application/octet-stream" (3974 bytes)
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