{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2021-47640", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-47640", "idYear": 2021, "status": "PUBLISHED", "publishedAt": "2025-02-26T01:54:12.130Z", "updatedAt": "2026-05-23T15:20:23.390Z", "importedAt": "2026-10-24T01:56:36.661Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "powerpc/kasan: Fix early region not updated correctly", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/kasan: Fix early region not updated correctly\n\nThe shadow's page table is not updated when PTE_RPN_SHIFT is 24\nand PAGE_SHIFT is 12. It not only causes false positives but\nalso false negative as shown the following text.\n\nFix it by bringing the logic of kasan_early_shadow_page_entry here.\n\n1. False Positive:\n==================================================================\nBUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50\nWrite of size 16 at addr f57f3be0 by task swapper/0/1\n\nCPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1\nCall Trace:\n[c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable)\n[c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300\n[c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200\n[c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0\n[c80d1cc0] [c03018a4] memset+0x34/0x90\n[c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50\n[c80d1d40] [c02fd7bc] __kmem_cache_create+0xfc/0x570\n[c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0\n[c80d1db0] [c2036580] init_sd+0xc4/0x1d0\n[c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c\n[c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384\n[c80d1ef0] [c0004b14] kernel_init+0x24/0x170\n[c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64\n\nMemory state around the buggy address:\n f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n>f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n ^\n f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n f57f3c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8\n==================================================================\n\n2. False Negative (with KASAN tests):\n==================================================================\nBefore fix:\n ok 45 - kmalloc_double_kzfree\n # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039\n KASAN failure expected in \"((volatile char *)area)[3100]\", but none occurred\n not ok 46 - vmalloc_oob\n not ok 1 - kasan\n\n==================================================================\nAfter fix:\n ok 1 - kasan", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "cbd18991e24fea2c31da3bb117c83e4a3538cd11", "status": "affected", "versionType": "git", "lessThan": "7f19245c3647afea8c7c41f795506ef70f64b9f2" }, { "version": "cbd18991e24fea2c31da3bb117c83e4a3538cd11", "status": "affected", "versionType": "git", "lessThan": "f39a3309393a4a484532f6ba745c6acbcfe06115" }, { "version": "cbd18991e24fea2c31da3bb117c83e4a3538cd11", "status": "affected", "versionType": "git", "lessThan": "5a3d8f3192a409893c57808cc935e16484df1068" }, { "version": "cbd18991e24fea2c31da3bb117c83e4a3538cd11", "status": "affected", "versionType": "git", "lessThan": "de56beace6648065d404cd9835aa7d30e3df519d" }, { "version": "cbd18991e24fea2c31da3bb117c83e4a3538cd11", "status": "affected", "versionType": "git", "lessThan": "e3d157a4b4f4e0268c98be5b7013bf4b31234bb6" }, { "version": "cbd18991e24fea2c31da3bb117c83e4a3538cd11", "status": "affected", "versionType": "git", "lessThan": "dd75080aa8409ce10d50fb58981c6b59bf8707d3" }, { "version": "3822dd8c102d11ada9d9ed8e04cad0b347a04689", "status": "affected", "versionType": "git" }, { "version": "5.3.6", "status": "affected", "versionType": "semver", "lessThan": "5.4" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "5.4", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "5.4" }, { "version": "5.4.189", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.4.*" }, { "version": "5.10.110", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.33", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "5.16.19", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.16.*" }, { "version": "5.17.2", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.17.*" }, { "version": "5.18", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }