Linux Distros 未修補弱點：CVE-2021-47350
medium Nessus Plugin ID 229794
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。- 在 Linux 核心中，已解決下列弱點： powerpc/mm: Fix lockup on kernel exec fault The powerpc kernel is not prepared to handle exec faults from kernel. Especially, the function is_exec_fault() will return 'false' when an exec fault is taken by kernel, because the check is based on reading current->thread.regs->trap which contains the trap from user. For instance, when provoking a LKDTM EXEC_USERSPACE test, current->thread.regs->trap is set to SYSCALL trap (0xc00), and the fault taken by the kernel is not seen as an exec fault by set_access_flags_filter(). Commit d7df2443cd5f (powerpc/mm: Fix spurious segfaults on radix with autonuma) made it clear and handled it properly. But later on commit d3ca587404b3 (powerpc/mm: Fix reporting of kernel execute faults) removed that handling, introducing test based on error_code. And here is the problem, because on the 603 all upper bits of SRR1 get cleared when the TLB instruction miss handler bails out to ISI. Until commit cbd7e6ca0210 (powerpc/fault: Avoid heavy search_exception_tables() verification), an exec fault from kernel at a userspace address was indirectly caught by the lack of entry for that address in the exception tables. But after that commit the kernel mainly relies on KUAP or on core mm handling to catch wrong user accesses. Here the access is not wrong, so mm handles it. It is a minor fault because PAGE_EXEC is not set, set_access_flags_filter() should set PAGE_EXEC and voila. But as is_exec_fault() returns false as explained in the beginning, set_access_flags_filter() bails out without setting PAGE_EXEC flag, which leads to a forever minor exec fault. As the kernel is not prepared to handle such exec faults, the thing to do is to fire in bad_kernel_fault() for any exec fault taken by the kernel, as it was prior to commit d3ca587404b3.
(CVE-2021-47350)
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。Plugin 詳細資訊
嚴重性: Medium
ID: 229794
檔案名稱: unpatched_CVE_2021_47350.nasl
版本: 1.1
類型: local
代理程式: unix
系列: Misc.
已發布: 2025/3/5
已更新: 2025/3/5
支援的感應器: Nessus Agent, Nessus
風險資訊
VPR
風險因素: Medium
分數: 4.4
CVSS v2
風險因素: Medium
基本分數: 4.6
時間性分數: 3.4
媒介: CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C
CVSS 評分資料來源: CVE-2021-47350
CVSS v3
風險因素: Medium
基本分數: 5.5
時間性分數: 4.8
媒介: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
時間媒介: CVSS:3.0/E:U/RL:O/RC:C
弱點資訊
必要的 KB 項目: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched
可輕鬆利用: No known exploits are available
弱點發布日期: 2024/5/21
參考資訊
CVE: CVE-2021-47350