Linux Distros 未修補的弱點：CVE-2021-47094
high Nessus Plugin ID 224446
語言:
概要
Linux/Unix 主機上安裝的一個或多個套件存有弱點，供應商表示將不會修補。說明
Linux/Unix 主機上安裝了一個或多個受到弱點影響的套件，且廠商未提供可用的修補程式。- KVMx86/mmu因為讓道而導致在重新啟動後不前進迭代器將 TDP MMU 中的 mmu_lock 放置到 tdp_iter_next() 期間重新啟動迭代器且不要前進迭代器。前進 iterator 會導致略過最上層的 SPTE 及其所有子項這如果有任何略過的 SPTE 在產生之前未遭到造訪就會很嚴重。當切換所有 SPTE 時 (即 min_level == root_level) 如果目前 gfn 具有作為有效的 SPTE重新啟動 iter 然後叫用 tdp_iter_next() 一律會發生嚴重後果因為將 iterator 推進會導致 try_step_side() 略過目前的 gfn而其並非yield 之前不曾造訪。在各種通常與 yielding 搭配使用的協助程式中當 iter->yielded 為 true 時散佈警告並以 __must_check 標記協助程式以降低不當使用的可能性。無法以以下兩種方式之一對頂層 SPTE 資訊清單進行 zap。如果 kvm_tdp_mmu_zap_all() 和 kvm_tdp_mmu_put_root() 略過有效的 SPTE就會洩漏陰影頁面且 KVM 會發出相應的警告。警告 CPU: 1 PID: 3509 at arch/x86/kvm/mmu/tdp_mmu.c:46 [kvm] RIP
0010kvm_mmu_uninit_tdp_mmu+0x3e/0x50 [kvm] 呼叫追踪 <TASK> kvm_arch_destroy_vm+0x130/0x1b0 [kvm] kvm_destroy_vm+0x162/0x2a0 [kvm] kvm_vcpu_release+0x34/0x60 [kvm] __fput+0x5/x2400 task_run_exit+0x +0x364/0xa10 ? futex_unqueue+0x38/0x60 do_group_exit+0x33/0xa0 get_signal+0x155/0x850 arch_do_signal_or_restart+0xed/0x750 exit_to_user_mode_prepare+0xc5/0x120 syscall_exit_to_user_mode+0x1d/0x40 do_syscall_64+0x48/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae If kvm_tdp_mmu_zap_all() skips a gfn/SPTE but SPTE 之後被 kvm_tdp_mmu_put_root() 刪除時KVM 會在將結構頁面放回釋放清單後將其標記為已變更/已存取會觸發釋放後使用情形。這會因為遇到 page_count() == 0 的頁面而直接觸發 WARN但也可能導致核心中的資料損毀和其他錯誤。警告arch/x86/kvm/../../../virt/kvm/kvm_main.c:171 RIP: 0010:kvm_is_zone_device_pfn.part.0+0x9e/0xd0 [kvm] 呼叫的 CPU: 7 PID: 1995658 Trace <TASK> kvm_set_pfn_dirty+0x120/0x1d0 [kvm] __handle_changed_spte+0x92e/0xca0 [kvm]
__handle_changed_spte+0x63c/0xca0 [kvm] __handle_changed_spte+0x63c/0xca0 [kvm]
__handle_changed_spte+0x63c/0xca0 [kvm] zap_gfn_range+0x549/0x620 [kvm] kvm_tdp_mmu_put_root+0x1b6/0x270 [kvm] mmu_free_root_page+0x219/0x2c0 [kvm] kvm_mmu_free_roots+0x1b4/0x4e0 [kvm] kvm_mmu_unload+0x1c/0xa0 [kvm] kvm_arch_destroy_vm+ 0x1f2/0x5c0 [kvm] kvm_put_kvm+0x3b1/0x8b0 [kvm] kvm_vcpu_release+0x4e/0x70 [kvm]
__fput+0x1f7/0x8c0 task_work_run+0xf8/0x1a0 do_exit+0x97b/0x2230 do_group_exit+0xda/0x2a0 get_signal+0x3be/0x1e50 arch_do_signal_or_restart+0x244/0x17f0 exit_to_user_mode_prepare+0xcb/0x120 syscall_exit_to_user_mode+0x1d/0x40 do_syscall_64+0x4d/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae請注意即使在認可 1af4a96025b3 (KVMx86/mmu即使沒有 SPTES 未變更TDU MMU iter 中的 Yield) 將 tdp_mmu_iter_cond_resched() 的呼叫移至迴圈開頭之前就存在基礎錯誤因為 KVM 仍可能不正確地前進超過 top-在較低層級項目上讓台時執行層級項目。但就洩漏陰影頁面而言在處理目前的 gfn 之前yield 會引入錯誤。或者tdp_mmu_iter_cond_resched() 可能會輕易失敗或呼叫者可能跳至其重試標籤。該方法的不利之處在於 _必須_在迴圈中的任何其他項目之前_呼叫 tdp_mmu_iter_cond_resched()而且沒有簡單的方法可以強制執行該要求。理想情況下KVM 會完全在 iterator 巨集中處理 cond_resched() (程式碼實際上相當乾淨) 並避免整個這類錯誤不過這非常困難。wh ---truncated--- (CVE-2021-47094)
請注意，Nessus 的判定取決於廠商所報告的套件是否存在。
解決方案
目前尚未有已知的解決方案。另請參閱
https://access.redhat.com/security/cve/cve-2021-47094
Plugin 詳細資訊
嚴重性: High
ID: 224446
檔案名稱: unpatched_CVE_2021_47094.nasl
版本: 1.3
類型: local
代理程式: unix
系列: Misc.
已發布: 2025/3/5
已更新: 2025/9/5
支援的感應器: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus
風險資訊
VPR
風險因素: Medium
分數: 6.0
CVSS v2
風險因素: Medium
基本分數: 5.6
時間性分數: 4.1
媒介: CVSS2#AV:L/AC:H/Au:N/C:N/I:C/A:C
CVSS 評分資料來源: CVE-2021-47094
CVSS v3
風險因素: High
基本分數: 7.1
時間性分數: 6.2
媒介: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
時間媒介: CVSS:3.0/E:U/RL:O/RC:C
弱點資訊
CPE: p-cpe:/a:redhat:enterprise_linux:kernel-rt-selftests-internal, p-cpe:/a:centos:centos:kernel-headers, p-cpe:/a:centos:centos:kernel-rt-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules, p-cpe:/a:redhat:enterprise_linux:kernel-debug, p-cpe:/a:canonical:ubuntu_linux:linux-hwe, p-cpe:/a:redhat:enterprise_linux:kernel-modules, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, p-cpe:/a:redhat:enterprise_linux:kernel-tools, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-edge, p-cpe:/a:canonical:ubuntu_linux:linux-intel-5.13, cpe:/o:centos:centos:8, p-cpe:/a:centos:centos:kernel-zfcpdump-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-rt-core, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.17, p-cpe:/a:redhat:enterprise_linux:kernel, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-internal, p-cpe:/a:centos:centos:kernel-modules-extra, p-cpe:/a:centos:centos:kernel-cross-headers, p-cpe:/a:canonical:ubuntu_linux:linux-gcp, p-cpe:/a:centos:centos:kernel-doc, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.15, p-cpe:/a:centos:centos:kernel-tools-libs, p-cpe:/a:centos:centos:kernel-debug-modules, p-cpe:/a:redhat:enterprise_linux:kernel-ipaclones-internal, p-cpe:/a:centos:centos:kernel-rt-debug-kvm, p-cpe:/a:centos:centos:kernel-rt-debug-devel, cpe:/o:debian:debian_linux:11.0, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-5.19, p-cpe:/a:centos:centos:kernel-rt-devel, p-cpe:/a:centos:centos:kernel-rt-selftests-internal, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.0, p-cpe:/a:redhat:enterprise_linux:bpftool, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.2, p-cpe:/a:centos:centos:bpftool, p-cpe:/a:centos:centos:kernel-core, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.11, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug, p-cpe:/a:centos:centos:kernel-rt-core, p-cpe:/a:centos:centos:kernel-zfcpdump, p-cpe:/a:redhat:enterprise_linux:kernel-abi-whitelists, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-devel, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.8, p-cpe:/a:redhat:enterprise_linux:kernel-devel, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-5.19, p-cpe:/a:centos:centos:kernel-rt-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-azure, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.3, p-cpe:/a:redhat:enterprise_linux:python3-perf, p-cpe:/a:redhat:enterprise_linux:kernel-rt, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump, p-cpe:/a:canonical:ubuntu_linux:linux-gke, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.19, p-cpe:/a:debian:debian_linux:linux, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-riscv, p-cpe:/a:centos:centos:kernel-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.2, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs, p-cpe:/a:canonical:ubuntu_linux:linux-oem, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.19, p-cpe:/a:centos:centos:kernel-rt-debug, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-gkeop-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-allwinner-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.2, p-cpe:/a:centos:centos:kernel-modules, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.11, p-cpe:/a:redhat:enterprise_linux:kernel-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.3, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:perf, p-cpe:/a:redhat:enterprise_linux:kernel-abi-stablelists, p-cpe:/a:centos:centos:kernel-rt-modules, p-cpe:/a:centos:centos:kernel-tools, p-cpe:/a:centos:centos:kernel-abi-stablelists, p-cpe:/a:redhat:enterprise_linux:kernel-debug-core, p-cpe:/a:centos:centos:kernel-zfcpdump-devel, cpe:/o:redhat:enterprise_linux:8, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-azure-edge, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde, p-cpe:/a:centos:centos:kernel-rt-debug-modules, p-cpe:/a:redhat:enterprise_linux:kernel-core, p-cpe:/a:centos:centos:kernel-rt-debug-modules-extra, p-cpe:/a:centos:centos:kernel-zfcpdump-core, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.3, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-core, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.0, p-cpe:/a:centos:centos:kernel-zfcpdump-modules, p-cpe:/a:centos:centos:kernel-rt-debug-modules-internal, p-cpe:/a:centos:centos:kernel-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.0, p-cpe:/a:centos:centos:kernel-rt-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs-devel, p-cpe:/a:redhat:enterprise_linux:kernel-cross-headers, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.2, p-cpe:/a:centos:centos:kernel-tools-libs-devel, p-cpe:/a:centos:centos:kernel-debug, p-cpe:/a:centos:centos:kernel-selftests-internal, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.8, p-cpe:/a:centos:centos:perf, p-cpe:/a:redhat:enterprise_linux:kernel-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.13, p-cpe:/a:centos:centos:kernel, p-cpe:/a:canonical:ubuntu_linux:linux-raspi2, p-cpe:/a:centos:centos:kernel-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-selftests-internal, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.2, p-cpe:/a:redhat:enterprise_linux:kernel-headers, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.10, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.8, p-cpe:/a:redhat:enterprise_linux:kernel-rt-kvm, p-cpe:/a:centos:centos:kernel-ipaclones-internal, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.19, p-cpe:/a:redhat:enterprise_linux:kernel-doc, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.13, p-cpe:/a:centos:centos:kernel-debug-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-devel, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.6, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.11, p-cpe:/a:centos:centos:kernel-modules-internal, p-cpe:/a:centos:centos:kernel-rt-debug-core, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.1, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-devel, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.8, p-cpe:/a:centos:centos:kernel-abi-whitelists, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.19, p-cpe:/a:centos:centos:kernel-zfcpdump-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-gke-4.15, p-cpe:/a:centos:centos:kernel-debug-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-6.2, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:centos:centos:python3-perf, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.14, p-cpe:/a:centos:centos:kernel-rt, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-6.2
必要的 KB 項目: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier
可輕鬆利用: No known exploits are available
弱點發布日期: 2024/3/4
參考資訊
CVE: CVE-2021-47094