libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo()

{
  "id": "98cea6978b438b442ecddbdc77f6c00cd7dfcd3052bead23b80709f0d3ef0905",
  "url": "https://osv.dev/vulnerability/CVE-2026-64596",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo() Since commit 1e7ab6f67824 (\"anon_inode: rework assertions\"), path_noexec() warns when an anonymous-inode file is mmap'd from a superblock that has not set SB_I_NOEXEC. dma-buf backs its files this way and never set the flag, so mmap of any exported buffer trips the warning on a CONFIG_DEBUG_VFS=y kernel: WARNING: CPU: 11 PID: 121813 at fs/exec.c:118 path_noexec+0x47/0x50 do_mmap+0x2b5/0x680 vm_mmap_pgoff+0x129/0x210 ksys_mmap_pgoff+0x177/0x240 __x64_sys_mmap+0x33/0x70 init_pseudo() sets up internal SB_NOUSER mounts that are never path-reachable. Set both flags here so every pseudo filesystem gets them by default instead of each caller setting them. SB_I_NODEV is inert for unreachable mounts. SB_I_NOEXEC has one visible effect: an executable mapping of a pseudo-fs fd, such as a dma-buf, now fails with -EPERM, which is the invariant the assertion enforces. No in-tree caller maps these executable. Reproduce on CONFIG_DEBUG_VFS=y: make -C tools/testing/selftests/dmabuf-heaps sudo ./tools/testing/selftests/dmabuf-heaps/dmabuf-heap -t system",
    "evidence": "osv:CVE-2026-64596",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.39",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-64596",
      "aliases": [
        "CVE-2026-64596"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "1e7ab6f67824343ee3e96f100f0937c393749a8a"
                },
                {
                  "fixed": "b9d45d328fcda4f0d3d281b7d6f12d3f181d9381"
                },
                {
                  "fixed": "8e931557b317f0fb414839fa51fae1d5feb0ad97"
                },
                {
                  "fixed": "6de2aeffabaafaeda819e60ec8d04f199711e11a"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "6.15.6"
                },
                {
                  "fixed": "6.16"
                }
              ]
            },
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "9b8076a9404568d6cb6673b9a079558b15051966"
                }
              ]
            }
          ],
          "versions": [
            "v6.15.11",
            "v6.15.10",
            "v6.15.9",
            "v6.15.8",
            "v6.15.7",
            "v6.15.6"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64596.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.16.0"
                },
                {
                  "fixed": "6.18.39"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64596.json"
          }
        }
      ],
      "modified": "2026-10-08T02:51:31.132034094Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/6de2aeffabaafaeda819e60ec8d04f199711e11a",
        "https://git.kernel.org/stable/c/8e931557b317f0fb414839fa51fae1d5feb0ad97",
        "https://git.kernel.org/stable/c/b9d45d328fcda4f0d3d281b7d6f12d3f181d9381",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64596.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64596",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64596.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64596",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 98320,
  "published_at": "2026-08-06T07:13:51.523+00:00"
}