Linux Distros 未修補的弱點：CVE-2025-21977
medium Nessus Plugin ID 244428
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，且供應商未提供可用的修補程式。- 已解決 Linux 核心中的下列弱點：fbdev: hyperv_fb: Fix hang in kdump kernel when on Hyper-V Gen 2 VMs Gen 2 Hyper-V VMs boot via EFI and have a standard EFI framebuffer device. When the kdump kernel runs in such a VM, loading the efifb driver may hang because of accessing the framebuffer at the wrong memory address. The scenario occurs when the hyperv_fb driver in the original kernel moves the framebuffer to a different MMIO address because of conflicts with an already-running efifb or simplefb driver. The hyperv_fb driver then informs Hyper-V of the change, which is allowed by the Hyper-V FB VMBus device protocol. However, when the kexec command loads the kdump kernel into crash memory via the kexec_file_load() system call, the system call doesn't know the framebuffer has moved, and it sets up the kdump screen_info using the original framebuffer address. The transition to the kdump kernel does not go through the Hyper-V host, so Hyper-V does not reset the framebuffer address like it would do on a reboot. When efifb tries to run, it accesses a non-existent framebuffer address, which traps to the Hyper-V host. After many such accesses, the Hyper-V host thinks the guest is being malicious, and throttles the guest to the point that it runs very slowly or appears to have hung. When the kdump kernel is loaded into crash memory via the kexec_load() system call, the problem does not occur. In this case, the kexec command builds the screen_info table itself in user space from data returned by the FBIOGET_FSCREENINFO ioctl against /dev/fb0, which gives it the new framebuffer location. This problem was originally reported in 2020 [1], resulting in commit 3cb73bc3fa2a (hyperv_fb: Update screen_info after removing old framebuffer). This commit solved the problem by setting orig_video_isVGA to 0, so the kdump kernel was unaware of the EFI framebuffer. The efifb driver did not try to load, and no hang occurred. But in 2024, commit c25a19afb81c (fbdev/hyperv_fb: Do not clear global screen_info) effectively reverted 3cb73bc3fa2a. Commit c25a19afb81c has no reference to 3cb73bc3fa2a, so perhaps it was done without knowing the implications that were reported with 3cb73bc3fa2a. In any case, as of commit c25a19afb81c, the original problem came back again. Interestingly, the hyperv_drm driver does not have this problem because it never moves the framebuffer. The difference is that the hyperv_drm driver removes any conflicting framebuffers *before* allocating an MMIO address, while the hyperv_fb drivers removes conflicting framebuffers *after* allocating an MMIO address. With the after ordering, hyperv_fb may encounter a conflict and move the framebuffer to a different MMIO address. But the conflict is essentially bogus because it is removed a few lines of code later. Rather than fix the problem with the approach from 2020 in commit 3cb73bc3fa2a, instead slightly reorder the steps in hyperv_fb so conflicting framebuffers are removed before allocating an MMIO address. Then the default framebuffer MMIO address should always be available, and there's never any confusion about which framebuffer address the kdump kernel should use -- it's always the original address provided by the Hyper-V host. This approach is already used by the hyperv_drm driver, and is consistent with the usage guidelines at the head of the module with the function aperture_remove_conflicting_devices(). This approach also solves a related minor problem when kexec_load() is used to load the kdump kernel. With current code, unbinding and rebinding the hyperv_fb driver could result in the framebuffer moving back to the default framebuffer address, because on the rebind there are no conflicts. If such a move is done after the kdump kernel is loaded with the new framebuffer address, at kdump time it could again have the wrong address. This problem and fix are described in terms of the kdump kernel, but it can also occur ---truncated--- (CVE-2025-21977)
請注意，Nessus 依賴供應商報告的套件存在。
解決方案
目前尚未有已知的解決方案。另請參閱
Plugin 詳細資訊
嚴重性: Medium
ID: 244428
檔案名稱: unpatched_CVE_2025_21977.nasl
版本: 1.5
類型: local
代理程式: unix
系列: Misc.
已發布: 2025/8/6
已更新: 2025/10/8
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: 5.2
CVSS v2
風險因素: Medium
基本分數: 4.9
時間性分數: 3.6
媒介: CVSS2#AV:L/AC:L/Au:N/C:N/I:N/A:C
CVSS 評分資料來源: CVE-2025-21977
CVSS v3
風險因素: Medium
基本分數: 5.6
時間性分數: 4.9
媒介: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:N/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:canonical:ubuntu_linux:linux-azure-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.0, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.5, cpe:/o:canonical:ubuntu_linux:24.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-oracle, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-riscv, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.17, p-cpe:/a:canonical:ubuntu_linux:linux-intel, p-cpe:/a:canonical:ubuntu_linux:linux-gcp, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-hwe, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-6.5, 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, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.3, 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:canonical:ubuntu_linux:linux-aws-5.0, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-gkeop-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-azure, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-raspi-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-gke, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.5, 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:canonical:ubuntu_linux:linux-oracle-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.0, p-cpe:/a:canonical:ubuntu_linux:linux-raspi2, p-cpe:/a:canonical:ubuntu_linux:linux-intel-iot-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-realtime, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.13, 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-gkeop, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.1, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-oem, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.19, cpe:/o:canonical:ubuntu_linux:25.04, 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-azure-nvidia, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-tegra, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.8, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-gke-4.15, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-6.2, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.5, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.14, 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: 2025/4/1
參考資訊
CVE: CVE-2025-21977