CVE-2026-46280 (GCVE-0-2026-46280)
Vulnerability from cvelistv5
Published
2026-06-08 15:41
Modified
2026-08-05 12:31
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: lib: test_hmm: evict device pages on file close to avoid use-after-free Patch series "Minor hmm_test fixes and cleanups". Two bugfixes a cleanup for the HMM kernel selftests. These were mostly reported by Zenghui Yu with special thanks to Lorenzo for analysing and pointing out the problems. This patch (of 3): When dmirror_fops_release() is called it frees the dmirror struct but doesn't migrate device private pages back to system memory first. This leaves those pages with a dangling zone_device_data pointer to the freed dmirror. If a subsequent fault occurs on those pages (eg. during coredump) the dmirror_devmem_fault() callback dereferences the stale pointer causing a kernel panic. This was reported [1] when running mm/ksft_hmm.sh on arm64, where a test failure triggered SIGABRT and the resulting coredump walked the VMAs faulting in the stale device private pages. Fix this by calling dmirror_device_evict_chunk() for each devmem chunk in dmirror_fops_release() to migrate all device private pages back to system memory before freeing the dmirror struct. The function is moved earlier in the file to avoid a forward declaration.
References
Impacted products
Vendor Product Version
Linux Linux Version: b2ef9f5a5cb37643ca5def3516c546457074b882
Version: b2ef9f5a5cb37643ca5def3516c546457074b882
Version: b2ef9f5a5cb37643ca5def3516c546457074b882
Version: b2ef9f5a5cb37643ca5def3516c546457074b882
Version: b2ef9f5a5cb37643ca5def3516c546457074b882
Version: b2ef9f5a5cb37643ca5def3516c546457074b882
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{
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      "cpeApplicability": [
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          "nodes": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlib: test_hmm: evict device pages on file close to avoid use-after-free\n\nPatch series \"Minor hmm_test fixes and cleanups\".\n\nTwo bugfixes a cleanup for the HMM kernel selftests.  These were mostly\nreported by Zenghui Yu with special thanks to Lorenzo for analysing and\npointing out the problems.\n\n\nThis patch (of 3):\n\nWhen dmirror_fops_release() is called it frees the dmirror struct but\ndoesn\u0027t migrate device private pages back to system memory first.  This\nleaves those pages with a dangling zone_device_data pointer to the freed\ndmirror.\n\nIf a subsequent fault occurs on those pages (eg.  during coredump) the\ndmirror_devmem_fault() callback dereferences the stale pointer causing a\nkernel panic.  This was reported [1] when running mm/ksft_hmm.sh on arm64,\nwhere a test failure triggered SIGABRT and the resulting coredump walked\nthe VMAs faulting in the stale device private pages.\n\nFix this by calling dmirror_device_evict_chunk() for each devmem chunk in\ndmirror_fops_release() to migrate all device private pages back to system\nmemory before freeing the dmirror struct.  The function is moved earlier\nin the file to avoid a forward declaration."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires local syscalls to open the hmm_dmirror character device, issue HMM_DMIRROR_MIGRATE_TO_DEV ioctl, close the fd, and fault migrated pages; there is no network, adjacent-wireless, or physical-device attack path.\nAC:L - The UAF is deterministically triggered by the attacker\u0027s own migrate-then-close-then-fault sequence with no race or external timing dependency; the attacker fully controls both sides of the lifecycle.\nPR:L - The vulnerable ioctl and release paths perform no capability or permission checks beyond opening the local character device; any local user who can access /dev/hmm_dmirrorN can execute the full exploit chain without real root privileges in the init namespace.\nUI:N - No victim interaction is required; the attacker triggers the fault themselves by accessing their own migrated pages or aborting for coredump after closing the device file.\nS:U - Impact is confined to kernel memory corruption and panic within the same kernel security boundary; this is a test-module UAF, not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.\nC:H - The stale dmirror pointer is dereferenced in dmirror_devmem_fault() to read freed kmalloc memory (dmirror-\u003emdevice, dmirror-\u003eflags), giving a classic UAF information-disclosure primitive.\nI:H - The fault handler continues to use the freed dmirror for migration and xa_erase on dmirror-\u003ept, enabling heap reuse attacks and arbitrary kernel memory write or code-execution primitives.\nA:H - The bug was reported to cause kernel panic during coredump VMA walks, and any UAF page fault on stale device-private pages can oops or panic the system."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:31:01.052Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/234071b4318feaeb27cd2e4e1b16ef6b055adf89"
        },
        {
          "url": "https://git.kernel.org/stable/c/bf477abd448c76bb8ea51c9b4f63a3a17c4b6239"
        },
        {
          "url": "https://git.kernel.org/stable/c/5846715b6382dd4c6a69b35a56ca6115d33bc2a0"
        },
        {
          "url": "https://git.kernel.org/stable/c/38f113f81d3f0adc658a4475dd3ecaec985e21d3"
        },
        {
          "url": "https://git.kernel.org/stable/c/9de1eb0aac2862d6144b8db0ec1388e79f8bc3e1"
        },
        {
          "url": "https://git.kernel.org/stable/c/744dd97752ef1076a8d8672bb0d8aa2c7abc1144"
        }
      ],
      "title": "lib: test_hmm: evict device pages on file close to avoid use-after-free",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-46280",
    "datePublished": "2026-06-08T15:41:23.095Z",
    "dateReserved": "2026-05-13T15:03:33.110Z",
    "dateUpdated": "2026-08-05T12:31:01.052Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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