{
   "containers": {
      "cna": {
         "providerMetadata": {
            "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038"
         },
         "descriptions": [
            {
               "lang": "en",
               "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: nVMX: Always make an attempt to map eVMCS after migration\n\nWhen enlightened VMCS is in use and nested state is migrated with\nvmx_get_nested_state()/vmx_set_nested_state() KVM can't map evmcs\npage right away: evmcs gpa is not 'struct kvm_vmx_nested_state_hdr'\nand we can't read it from VP assist page because userspace may decide\nto restore HV_X64_MSR_VP_ASSIST_PAGE after restoring nested state\n(and QEMU, for example, does exactly that). To make sure eVMCS is\nmapped /vmx_set_nested_state() raises KVM_REQ_GET_NESTED_STATE_PAGES\nrequest.\n\nCommit f2c7ef3ba955 (\"KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES\non nested vmexit\") added KVM_REQ_GET_NESTED_STATE_PAGES clearing to\nnested_vmx_vmexit() to make sure MSR permission bitmap is not switched\nwhen an immediate exit from L2 to L1 happens right after migration (caused\nby a pending event, for example). Unfortunately, in the exact same\nsituation we still need to have eVMCS mapped so\nnested_sync_vmcs12_to_shadow() reflects changes in VMCS12 to eVMCS.\n\nAs a band-aid, restore nested_get_evmcs_page() when clearing\nKVM_REQ_GET_NESTED_STATE_PAGES in nested_vmx_vmexit(). The 'fix' is far\nfrom being ideal as we can't easily propagate possible failures and even if\nwe could, this is most likely already too late to do so. The whole\n'KVM_REQ_GET_NESTED_STATE_PAGES' idea for mapping eVMCS after migration\nseems to be fragile as we diverge too much from the 'native' path when\nvmptr loading happens on vmx_set_nested_state()."
            }
         ],
         "affected": [
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "unaffected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "arch/x86/kvm/vmx/nested.c"
               ],
               "versions": [
                  {
                     "version": "0faceb7d6dda",
                     "lessThan": "c8bf64e3fb77",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "f2c7ef3ba955",
                     "lessThan": "200a45649ab7",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "f2c7ef3ba955",
                     "lessThan": "bd0e8455b85b",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "f2c7ef3ba955",
                     "lessThan": "f5c7e8425f18",
                     "status": "affected",
                     "versionType": "git"
                  }
               ]
            },
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "affected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "arch/x86/kvm/vmx/nested.c"
               ],
               "versions": [
                  {
                     "version": "5.11",
                     "status": "affected"
                  },
                  {
                     "version": "0",
                     "lessThan": "5.11",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.10.38",
                     "lessThanOrEqual": "5.10.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.11.22",
                     "lessThanOrEqual": "5.11.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.12.5",
                     "lessThanOrEqual": "5.12.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.13",
                     "lessThanOrEqual": "*",
                     "status": "unaffected",
                     "versionType": "original_commit_for_fix"
                  }
               ]
            }
         ],
         "references": [
            {
               "url": "https://git.kernel.org/stable/c/c8bf64e3fb77cc19bad146fbe26651985b117194"
            },
            {
               "url": "https://git.kernel.org/stable/c/200a45649ab7361bc80c70aebf7165b64f9a6c9f"
            },
            {
               "url": "https://git.kernel.org/stable/c/bd0e8455b85b651a4c77de9616e307129b15aaa7"
            },
            {
               "url": "https://git.kernel.org/stable/c/f5c7e8425f18fdb9bdb7d13340651d7876890329"
            }
         ],
         "title": "KVM: nVMX: Always make an attempt to map eVMCS after migration",
         "x_generator": {
            "engine": "bippy-a5840b7849dd"
         }
      }
   },
   "cveMetadata": {
      "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038",
      "cveID": "CVE-2021-46978",
      "requesterUserId": "gregkh@kernel.org",
      "serial": "1",
      "state": "PUBLISHED"
   },
   "dataType": "CVE_RECORD",
   "dataVersion": "5.0"
}