Linux Distros 未修补的漏洞：CVE-2021-46910
medium Nessus 插件 ID 248926
语言：
简介
Linux/Unix 主机上安装的一个或多个程序包存在漏洞，但供应商表示不会修补此漏洞。描述
Linux/Unix 主机中安装的一个或多个程序包受到一个漏洞影响，而供应商没有提供补丁程序。- 已修复 Linux 内核中的下列漏洞：ARM: 9063/1: mm: reduce maximum number of CPUs if DEBUG_KMAP_LOCAL is enabled The debugging code for kmap_local() doubles the number of per-CPU fixmap slots allocated for kmap_local(), in order to use half of them as guard regions. This causes the fixmap region to grow downwards beyond the start of its reserved window if the supported number of CPUs is large, and collide with the newly added virtual DT mapping right below it, which is obviously not good.
One manifestation of this is EFI boot on a kernel built with NR_CPUS=32 and CONFIG_DEBUG_KMAP_LOCAL=y, which may pass the FDT in highmem, resulting in block entries below the fixmap region that the fixmap code misidentifies as fixmap table entries, and subsequently tries to dereference using a phys-to-virt translation that is only valid for lowmem. This results in a cryptic splat such as the one below. ftrace:
allocating 45548 entries in 89 pages 8<--- cut here --- Unable to handle kernel paging request at virtual address fc6006f0 pgd = (ptrval) [fc6006f0] *pgd=80000040207003, *pmd=00000000 Internal error: Oops: a06 [#1] SMP ARM Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 5.11.0+ #382 Hardware name:
Generic DT based system PC is at cpu_ca15_set_pte_ext+0x24/0x30 LR is at __set_fixmap+0xe4/0x118 pc :
[<c041ac9c>] lr : [<c04189d8>] psr: 400000d3 sp : c1601ed8 ip : 00400000 fp : 00800000 r10: 0000071f r9 :
00421000 r8 : 00c00000 r7 : 00c00000 r6 : 0000071f r5 : ffade000 r4 : 4040171f r3 : 00c00000 r2 : 4040171f r1 : c041ac78 r0 : fc6006f0 Flags: nZcv IRQs off FIQs off Mode SVC_32 ISA ARM Segment none Control:
30c5387d Table: 40203000 DAC: 00000001 Process swapper (pid: 0, stack limit = 0x(ptrval)) So let's limit CONFIG_NR_CPUS to 16 when CONFIG_DEBUG_KMAP_LOCAL=y. Also, fix the BUILD_BUG_ON() check that was supposed to catch this, by checking whether the region grows below the start address rather than above the end address. (CVE-2021-46910)
请注意，Nessus 依赖供应商报告的程序包是否存在进行判断。
解决方案
目前尚未有任何已知的解决方案。另见
插件详情
严重性: Medium
ID: 248926
文件名: unpatched_CVE_2021_46910.nasl
版本: 1.1
类型: local
代理: unix
系列: Misc.
发布时间: 2025/8/12
最近更新时间: 2025/8/12
支持的传感器: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus
风险信息
VPR
风险因素: Medium
分数: 4.4
CVSS v2
风险因素: High
基本分数: 7.2
时间分数: 5.3
矢量: CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C
CVSS 分数来源: CVE-2021-46910
CVSS v3
风险因素: Medium
基本分数: 5.5
时间分数: 4.8
矢量: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
时间矢量: CVSS:3.0/E:U/RL:O/RC:C
漏洞信息
CPE: cpe:/o:canonical:ubuntu_linux:16.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-edge, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-hwe, p-cpe:/a:canonical:ubuntu_linux:linux-intel-5.13, 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-azure-5.19, 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-gcp-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.15, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.17, p-cpe:/a:canonical:ubuntu_linux:linux-gcp, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-azure-edge, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-azure, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde, 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-aws-6.2, 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-oem, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-gke, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-allwinner-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.0, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.0, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.2, 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-raspi2, 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-hwe-5.19, 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-starfive-6.2, 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, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.8, 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-gcp-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.1, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.13, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-gke-4.15, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.8
必需的 KB 项: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier
易利用性: No known exploits are available
漏洞发布日期: 2024/2/27
参考资料信息
CVE: CVE-2021-46910