Date: Fri, 05 Mar 2021 17:07:49 +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 v2 (CVE-2021-28038) - Linux: netback fails to honor grant mapping errors -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Xen Security Advisory CVE-2021-28038 / XSA-367 version 2 Linux: netback fails to honor grant mapping errors UPDATES IN VERSION 2 ==================== CVE assigned. 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/4UyVfoK9kFAmBCZVEMHHBncEB4ZW4u b3JnAAoJEIP+FMlX6CvZfqAH/i7ypTUP90UIxeyMB9XmNRiqD+LaTSBExt8xTowd zbsWrxFYnZRPSLqs/dVHlDQfF65eD40Agh/Hxp5f0hGHjv8x1kepvpo2di1ovA2h C8/WpOK2nFq77/GTG2mAsJA3ltDF0WJsr5oqaBNVf/lwQSmiescTWtI6+LDFmmpd q1EyKPUClKZW3PoZkCVmiWDtqhVJc3LaJJcy4x/Zd4EgV+uGi2wsYsiQzObrwPss 2D5laUr8RJcSTE7+bXlMA8KnzrOZ6UqK1YIPSGIYBOJnhizGf9CBZCxcNTONWQFC zh1d9GAv93fugE37xRHE7PRjgl/RVO5rn0k5EQw5GTa676A= =GKdV -----END PGP SIGNATURE----- Download attachment "xsa367-linux.patch" of type "application/octet-stream" (3974 bytes)
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