{
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            "rust/bindings/bindings_helper.h"
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            "rust/bindings/bindings_helper.h"
          ],
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          "vendor": "Linux",
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            },
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              "version": "0",
              "versionType": "semver"
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              "versionType": "original_commit_for_fix"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/ksm: fix flag-dropping behavior in ksm_madvise\n\nsyzkaller discovered the following crash: (kernel BUG)\n\n[   44.607039] ------------[ cut here ]------------\n[   44.607422] kernel BUG at mm/userfaultfd.c:2067!\n[   44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\n[   44.608814] CPU: 1 UID: 0 PID: 2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none)\n[   44.609635] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\n[   44.610695] RIP: 0010:userfaultfd_release_all+0x3a8/0x460\n\n\u003csnip other registers, drop unreliable trace\u003e\n\n[   44.617726] Call Trace:\n[   44.617926]  \u003cTASK\u003e\n[   44.619284]  userfaultfd_release+0xef/0x1b0\n[   44.620976]  __fput+0x3f9/0xb60\n[   44.621240]  fput_close_sync+0x110/0x210\n[   44.622222]  __x64_sys_close+0x8f/0x120\n[   44.622530]  do_syscall_64+0x5b/0x2f0\n[   44.622840]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n[   44.623244] RIP: 0033:0x7f365bb3f227\n\nKernel panics because it detects UFFD inconsistency during\nuserfaultfd_release_all().  Specifically, a VMA which has a valid pointer\nto vma-\u003evm_userfaultfd_ctx, but no UFFD flags in vma-\u003evm_flags.\n\nThe inconsistency is caused in ksm_madvise(): when user calls madvise()\nwith MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode,\nit accidentally clears all flags stored in the upper 32 bits of\nvma-\u003evm_flags.\n\nAssuming x86_64 kernel build, unsigned long is 64-bit and unsigned int and\nint are 32-bit wide.  This setup causes the following mishap during the \u0026=\n~VM_MERGEABLE assignment.\n\nVM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000\u00270000. \nAfter ~ is applied, it becomes 0x7fff\u0027ffff unsigned int, which is then\npromoted to unsigned long before the \u0026 operation.  This promotion fills\nupper 32 bits with leading 0s, as we\u0027re doing unsigned conversion (and\neven for a signed conversion, this wouldn\u0027t help as the leading bit is 0).\n\u0026 operation thus ends up AND-ing vm_flags with 0x0000\u00270000\u00277fff\u0027ffff\ninstead of intended 0xffff\u0027ffff\u00277fff\u0027ffff and hence accidentally clears\nthe upper 32-bits of its value.\n\nFix it by changing `VM_MERGEABLE` constant to unsigned long, using the\nBIT() macro.\n\nNote: other VM_* flags are not affected: This only happens to the\nVM_MERGEABLE flag, as the other VM_* flags are all constants of type int\nand after ~ operation, they end up with leading 1 and are thus converted\nto unsigned long with leading 1s.\n\nNote 2:\nAfter commit 31defc3b01d9 (\"userfaultfd: remove (VM_)BUG_ON()s\"), this is\nno longer a kernel BUG, but a WARNING at the same place:\n\n[   45.595973] WARNING: CPU: 1 PID: 2474 at mm/userfaultfd.c:2067\n\nbut the root-cause (flag-drop) remains the same.\n\n[akpm@linux-foundation.org: rust bindgen wasn\u0027t able to handle BIT(), from Miguel]"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T21:41:19.151Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/850f1ea245bdc0ce6a3fd36bfb80d8cf9647cb71"
        },
        {
          "url": "https://git.kernel.org/stable/c/788e5385d0ff69cdba1cabccb9dab8d9647b9239"
        },
        {
          "url": "https://git.kernel.org/stable/c/b69f19244c2b6475c8a6eb72f0fb0d53509e48cd"
        },
        {
          "url": "https://git.kernel.org/stable/c/41cb9fd904fe0c39d52e82dd84dc3c96b7aa9693"
        },
        {
          "url": "https://git.kernel.org/stable/c/92b82e232b8d8b116ac6e57aeae7a6033db92c60"
        },
        {
          "url": "https://git.kernel.org/stable/c/ac50c6e0a8f91a02b681af81abb2362fbb67cc18"
        },
        {
          "url": "https://git.kernel.org/stable/c/76385629f45740b7888f8fcd83bde955b10f61fe"
        },
        {
          "url": "https://git.kernel.org/stable/c/f04aad36a07cc17b7a5d5b9a2d386ce6fae63e93"
        }
      ],
      "title": "mm/ksm: fix flag-dropping behavior in ksm_madvise",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40040",
    "datePublished": "2025-10-28T11:48:20.395Z",
    "dateReserved": "2025-04-16T07:20:57.154Z",
    "dateUpdated": "2026-05-11T21:41:19.151Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-40040",
      "date": "2026-06-18",
      "epss": "0.00316",
      "percentile": "0.23117"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40040\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-28T12:15:37.967\",\"lastModified\":\"2026-02-26T15:51:08.683\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmm/ksm: fix flag-dropping behavior in ksm_madvise\\n\\nsyzkaller discovered the following crash: (kernel BUG)\\n\\n[   44.607039] ------------[ cut here ]------------\\n[   44.607422] kernel BUG at mm/userfaultfd.c:2067!\\n[   44.608148] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\\n[   44.608814] CPU: 1 UID: 0 PID: 2475 Comm: reproducer Not tainted 6.16.0-rc6 #1 PREEMPT(none)\\n[   44.609635] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014\\n[   44.610695] RIP: 0010:userfaultfd_release_all+0x3a8/0x460\\n\\n\u003csnip other registers, drop unreliable trace\u003e\\n\\n[   44.617726] Call Trace:\\n[   44.617926]  \u003cTASK\u003e\\n[   44.619284]  userfaultfd_release+0xef/0x1b0\\n[   44.620976]  __fput+0x3f9/0xb60\\n[   44.621240]  fput_close_sync+0x110/0x210\\n[   44.622222]  __x64_sys_close+0x8f/0x120\\n[   44.622530]  do_syscall_64+0x5b/0x2f0\\n[   44.622840]  entry_SYSCALL_64_after_hwframe+0x76/0x7e\\n[   44.623244] RIP: 0033:0x7f365bb3f227\\n\\nKernel panics because it detects UFFD inconsistency during\\nuserfaultfd_release_all().  Specifically, a VMA which has a valid pointer\\nto vma-\u003evm_userfaultfd_ctx, but no UFFD flags in vma-\u003evm_flags.\\n\\nThe inconsistency is caused in ksm_madvise(): when user calls madvise()\\nwith MADV_UNMEARGEABLE on a VMA that is registered for UFFD in MINOR mode,\\nit accidentally clears all flags stored in the upper 32 bits of\\nvma-\u003evm_flags.\\n\\nAssuming x86_64 kernel build, unsigned long is 64-bit and unsigned int and\\nint are 32-bit wide.  This setup causes the following mishap during the \u0026=\\n~VM_MERGEABLE assignment.\\n\\nVM_MERGEABLE is a 32-bit constant of type unsigned int, 0x8000\u00270000. \\nAfter ~ is applied, it becomes 0x7fff\u0027ffff unsigned int, which is then\\npromoted to unsigned long before the \u0026 operation.  This promotion fills\\nupper 32 bits with leading 0s, as we\u0027re doing unsigned conversion (and\\neven for a signed conversion, this wouldn\u0027t help as the leading bit is 0).\\n\u0026 operation thus ends up AND-ing vm_flags with 0x0000\u00270000\u00277fff\u0027ffff\\ninstead of intended 0xffff\u0027ffff\u00277fff\u0027ffff and hence accidentally clears\\nthe upper 32-bits of its value.\\n\\nFix it by changing `VM_MERGEABLE` constant to unsigned long, using the\\nBIT() macro.\\n\\nNote: other VM_* flags are not affected: This only happens to the\\nVM_MERGEABLE flag, as the other VM_* flags are all constants of type int\\nand after ~ operation, they end up with leading 1 and are thus converted\\nto unsigned long with leading 1s.\\n\\nNote 2:\\nAfter commit 31defc3b01d9 (\\\"userfaultfd: remove (VM_)BUG_ON()s\\\"), this is\\nno longer a kernel BUG, but a WARNING at the same place:\\n\\n[   45.595973] WARNING: CPU: 1 PID: 2474 at mm/userfaultfd.c:2067\\n\\nbut the root-cause (flag-drop) remains the same.\\n\\n[akpm@linux-foundation.org: rust bindgen wasn\u0027t able to handle BIT(), from Miguel]\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"4.6\",\"versionEndExcluding\":\"5.4.302\",\"matchCriteriaId\":\"92D7EAC7-85AD-4A59-982E-28696A9CB495\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.5\",\"versionEndExcluding\":\"5.10.247\",\"matchCriteriaId\":\"FE19816A-13B7-4862-B963-A4DF36CA766A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11\",\"versionEndExcluding\":\"5.15.197\",\"matchCriteriaId\":\"06E8A34D-C8D8-461A-B8F8-0E420CC5E116\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.16\",\"versionEndExcluding\":\"6.1.158\",\"matchCriteriaId\":\"77B0D8DC-487F-497A-8C89-E7C8F6427586\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.114\",\"matchCriteriaId\":\"4EB737C8-40A2-4187-8371-FFB0D2615B8B\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.55\",\"matchCriteriaId\":\"516AE9B7-F899-4BF2-A81C-BAB0A37671FA\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.17.3\",\"matchCriteriaId\":\"F55A160F-1578-4C10-ABCB-F90B7E146ED8\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/41cb9fd904fe0c39d52e82dd84dc3c96b7aa9693\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/76385629f45740b7888f8fcd83bde955b10f61fe\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/788e5385d0ff69cdba1cabccb9dab8d9647b9239\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/850f1ea245bdc0ce6a3fd36bfb80d8cf9647cb71\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/92b82e232b8d8b116ac6e57aeae7a6033db92c60\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/ac50c6e0a8f91a02b681af81abb2362fbb67cc18\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/b69f19244c2b6475c8a6eb72f0fb0d53509e48cd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f04aad36a07cc17b7a5d5b9a2d386ce6fae63e93\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
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}