Linux Distros Unpatched Vulnerability : CVE-2021-47640

high Nessus Plugin ID 230100

Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

- In the Linux kernel, the following vulnerability has been resolved: powerpc/kasan: Fix early region not updated correctly The shadow's page table is not updated when PTE_RPN_SHIFT is 24 and PAGE_SHIFT is 12. It not only causes false positives but also false negative as shown the following text. Fix it by bringing the logic of kasan_early_shadow_page_entry here. 1. False Positive:
================================================================== BUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50 Write of size 16 at addr f57f3be0 by task swapper/0/1 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1 Call Trace: [c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable) [c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300 [c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200 [c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0 [c80d1cc0] [c03018a4] memset+0x34/0x90 [c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50 [c80d1d40] [c02fd7bc]
__kmem_cache_create+0xfc/0x570 [c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0 [c80d1db0] [c2036580] init_sd+0xc4/0x1d0 [c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c [c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384 [c80d1ef0] [c0004b14] kernel_init+0x24/0x170 [c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64 Memory state around the buggy address: f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3c80:
f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ================================================================== 2. False Negative (with KASAN tests):
================================================================== Before fix: ok 45 - kmalloc_double_kzfree # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039 KASAN failure expected in ((volatile char *)area)[3100], but none occurred not ok 46 - vmalloc_oob not ok 1 - kasan ================================================================== After fix: ok 1 - kasan (CVE-2021-47640)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

Plugin Details

Severity: High

ID: 230100

File Name: unpatched_CVE_2021_47640.nasl

Version: 1.1

Type: local

Agent: unix

Family: Misc.

Published: 3/5/2025

Updated: 3/5/2025

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: High

Base Score: 7.5

Temporal Score: 5.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2021-47640

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.2

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Required KB Items: Host/cpu, Host/local_checks_enabled, global_settings/vendor_unpatched

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 2/26/2025

Reference Information

CVE: CVE-2021-47640

Detections

Analytics