{
  "cveId": "CVE-2021-47640",
  "url": "https://patchblox.com/security/cve/CVE-2021-47640",
  "summary": "CVE-2021-47640 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47640, released February 26, 2025. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  powerpc/kasan: Fix early region not updated corr...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  powerpc/kasan: Fix early region not updated correctly  The shadow\u0027s 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\u002B0x508/0xa50 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\u002B0x4c/0x6c (unreliable) [c80d1c40] [c02ff668] print_address_description.constprop.0\u002B0x88/0x300 [c80d1c70] [c02ff45c] kasan_report\u002B0x1ec/0x200 [c80d1cb0] [c0300b20] kasan_check_range\u002B0x160/0x2f0 [c80d1cc0] [c03018a4] memset\u002B0x34/0x90 [c80d1ce0] [c0280108] pcpu_alloc\u002B0x508/0xa50 [c80d1d40] [c02fd7bc] __kmem_cache_create\u002B0xfc/0x570 [c80d1d70] [c0283d64] kmem_cache_create_usercopy\u002B0x274/0x3e0 [c80d1db0] [c2036580] init_sd\u002B0xc4/0x1d0 [c80d1de0] [c00044a0] do_one_initcall\u002B0xc0/0x33c [c80d1eb0] [c2001624] kernel_init_freeable\u002B0x2c8/0x384 [c80d1ef0] [c0004b14] kernel_init\u002B0x24/0x170 [c80d1f10] [c001b26c] ret_from_kernel_thread\u002B0x5c/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 \u003Ef57f3b80: 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 \u0022((volatile char *)area)[3100]\u0022, but none occurred     not ok 46 - vmalloc_oob     not ok 1 - kasan  ================================================================== After fix:     ok 1 - kasan",
  "published": "2025-02-26T06:37:05Z",
  "severity": "high",
  "cvss": 7.8,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.00261,
  "epssPercentile": 0.17892,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "5.17.3-1",
      "fix": "DEBIAN-CVE-2021-47640",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47640",
      "released": "2025-02-26T06:37:05Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "5.17.3-1",
      "fix": "DEBIAN-CVE-2021-47640",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47640",
      "released": "2025-02-26T06:37:05Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "5.17.3-1",
      "fix": "DEBIAN-CVE-2021-47640",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2021-47640",
      "released": "2025-02-26T06:37:05Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}