🛡️ UBUNTU-CVE-2021-47640
⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2025-02-26
Updated 2026-06-15
Modified 2026-06-03
Fix URL N/A

Affected Packages

Software From version Fixed in
linux 5.15.0-37.39
linux-allwinner-5.19
linux-aws 5.15.0-1011.14
linux-aws-5.0
linux-aws-5.11
linux-aws-5.13
linux-aws-5.19
linux-aws-5.3
linux-aws-5.4 5.4.0-1078.84~18.04.1
linux-aws-5.8
linux-aws-6.2
linux-aws-6.5
linux-aws-fips
linux-azure 5.15.0-1010.12
linux-azure-5.11
linux-azure-5.13
linux-azure-5.15 5.15.0-1008.9~20.04.1
linux-azure-5.19
linux-azure-5.3
linux-azure-5.4 5.4.0-1083.87~18.04.1
linux-azure-5.8
linux-azure-6.2
linux-azure-6.5
linux-azure-edge
linux-azure-fde
linux-azure-fde-5.19
linux-azure-fde-6.2
linux-azure-fips
linux-bluefield
linux-fips
linux-gcp 5.15.0-1008.12
linux-gcp-5.11
linux-gcp-5.13
linux-gcp-5.19
linux-gcp-5.3
linux-gcp-5.4 5.4.0-1078.84~18.04.1
linux-gcp-5.8
linux-gcp-6.2
linux-gcp-6.5
linux-gcp-fips
linux-gke 5.15.0-1008.10
linux-gke-4.15
linux-gke-5.15
linux-gke-5.4
linux-gkeop
linux-gkeop-5.15
linux-gkeop-5.4
linux-hwe
linux-hwe-5.11
linux-hwe-5.13
linux-hwe-5.15 5.15.0-41.44~20.04.1
linux-hwe-5.19
linux-hwe-5.4 5.4.0-117.132~18.04.1
linux-hwe-5.8
linux-hwe-6.2
linux-hwe-6.5
linux-hwe-edge
linux-ibm 5.15.0-1007.8
linux-ibm-5.4 5.4.0-1028.32~18.04.1
linux-intel-5.13
linux-intel-iot-realtime
linux-intel-iotg 5.15.0-1008.11
linux-intel-iotg-5.15 5.15.0-1008.11~20.04.1
linux-iot 5.4.0-1004.6
linux-kvm 5.15.0-1010.11
linux-lowlatency 5.15.0-37.39
linux-lowlatency-hwe-5.15 5.15.0-42.45~20.04.1
linux-lowlatency-hwe-5.19
linux-lowlatency-hwe-6.2
linux-lowlatency-hwe-6.5
linux-nvidia
linux-nvidia-6.2
linux-nvidia-6.5
linux-oem
linux-oem-5.10
linux-oem-5.13
linux-oem-5.14
linux-oem-5.17
linux-oem-5.6
linux-oem-6.0
linux-oem-6.1
linux-oem-6.5
linux-oracle 5.15.0-1009.12
linux-oracle-5.0
linux-oracle-5.11
linux-oracle-5.13
linux-oracle-5.3
linux-oracle-5.4 5.4.0-1076.83~18.04.1
linux-oracle-5.8
linux-oracle-6.5
linux-raspi 5.15.0-1011.13
linux-raspi-5.4 5.4.0-1065.75~18.04.1
linux-raspi-realtime
linux-raspi2
linux-realtime 5.15.0-1014.14
linux-riscv
linux-riscv-5.11
linux-riscv-5.19
linux-riscv-5.8
linux-riscv-6.5
linux-starfive-5.19
linux-starfive-6.2
linux-starfive-6.5

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