GHSA-8PJ3-87FR-9H94

Vulnerability from github – Published: 2026-10-18 18:32 – Updated: 2026-10-30 15:34
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

nitro_enclaves: fix use-after-free on SLOT_ALLOC failure

When ne_create_vm_ioctl() fails the SLOT_ALLOC request after anon_inode_getfile() has succeeded, the error path calls fput(enclave_file) and then frees ne_enclave.

In normal userspace context, fput() defers the final __fput() via task_work. ne_enclave_release() therefore runs after ne_enclave has already been freed and dereferences ne_enclave->slot_uid, causing a use-after-free: KASAN: slab-use-after-free in ne_enclave_release.

The enclave has no slot allocated and is not yet linked into the enclaves list on this error path, so ne_enclave_release() is expected to return early when slot_uid is zero. However, reading slot_uid already accesses the freed object.

Clear enclave_file->private_data before fput() on the error path. ne_enclave_release() then returns immediately when private_data is NULL, leaving the ioctl error path as the sole owner of ne_enclave. This is safe because the file has not been fd_install()'d yet.

Tested on an AWS EC2 m5.2xlarge with CONFIG_KASAN=y. Without the patch, the reproducer triggers a KASAN slab-use-after-free on every SLOT_ALLOC failure. With the patch, no KASAN report is produced and the SLOT_ALLOC error is still returned. Normal enclave creation and teardown are unaffected.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98775"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:31Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnitro_enclaves: fix use-after-free on SLOT_ALLOC failure\n\nWhen ne_create_vm_ioctl() fails the SLOT_ALLOC request after\nanon_inode_getfile() has succeeded, the error path calls\nfput(enclave_file) and then frees ne_enclave.\n\nIn normal userspace context, fput() defers the final __fput() via\ntask_work. ne_enclave_release() therefore runs after ne_enclave has\nalready been freed and dereferences ne_enclave-\u003eslot_uid, causing a\nuse-after-free: KASAN: slab-use-after-free in ne_enclave_release.\n\nThe enclave has no slot allocated and is not yet linked into the\nenclaves list on this error path, so ne_enclave_release() is expected\nto return early when slot_uid is zero. However, reading slot_uid\nalready accesses the freed object.\n\nClear enclave_file-\u003eprivate_data before fput() on the error path.\nne_enclave_release() then returns immediately when private_data is\nNULL, leaving the ioctl error path as the sole owner of ne_enclave.\nThis is safe because the file has not been fd_install()\u0027d yet.\n\nTested on an AWS EC2 m5.2xlarge with CONFIG_KASAN=y. Without the\npatch, the reproducer triggers a KASAN slab-use-after-free on every\nSLOT_ALLOC failure. With the patch, no KASAN report is produced and\nthe SLOT_ALLOC error is still returned. Normal enclave creation and\nteardown are unaffected.",
  "id": "GHSA-8pj3-87fr-9h94",
  "modified": "2026-10-30T15:34:00Z",
  "published": "2026-10-18T18:32:02Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98775"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/43f78b328f3907ca2f7424e15b7e45ffbf9fe21c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/466041d14f26dc2babd606a2e85dce08774112a6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/718965a5fcea47f7ec6accff55306317aadc3af3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8024c50b8763add7912b6d9830327ba73f994204"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8bde6f643ab6fe5e3e3f4c312f84ce327ecf39b2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9bc184a2eda8b773c88ecbff934001ad649b9cc1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dac89ed976d9826eae4703281d0d51b062b58eef"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f7fb6c2835ede1b8ad84cf7e78a528a9d0159b84"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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