ghsa-722p-jvv6-w5fv
Vulnerability from github
Published
2025-08-19 18:31
Modified
2025-08-28 15:30
Details

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

perf/core: Prevent VMA split of buffer mappings

The perf mmap code is careful about mmap()'ing the user page with the ringbuffer and additionally the auxiliary buffer, when the event supports it. Once the first mapping is established, subsequent mapping have to use the same offset and the same size in both cases. The reference counting for the ringbuffer and the auxiliary buffer depends on this being correct.

Though perf does not prevent that a related mapping is split via mmap(2), munmap(2) or mremap(2). A split of a VMA results in perf_mmap_open() calls, which take reference counts, but then the subsequent perf_mmap_close() calls are not longer fulfilling the offset and size checks. This leads to reference count leaks.

As perf already has the requirement for subsequent mappings to match the initial mapping, the obvious consequence is that VMA splits, caused by resizing of a mapping or partial unmapping, have to be prevented.

Implement the vm_operations_struct::may_split() callback and return unconditionally -EINVAL.

That ensures that the mapping offsets and sizes cannot be changed after the fact. Remapping to a different fixed address with the same size is still possible as it takes the references for the new mapping and drops those of the old mapping.

Show details on source website

To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2025-38563"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-08-19T17:15:32Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nperf/core: Prevent VMA split of buffer mappings\n\nThe perf mmap code is careful about mmap()\u0027ing the user page with the\nringbuffer and additionally the auxiliary buffer, when the event supports\nit. Once the first mapping is established, subsequent mapping have to use\nthe same offset and the same size in both cases. The reference counting for\nthe ringbuffer and the auxiliary buffer depends on this being correct.\n\nThough perf does not prevent that a related mapping is split via mmap(2),\nmunmap(2) or mremap(2). A split of a VMA results in perf_mmap_open() calls,\nwhich take reference counts, but then the subsequent perf_mmap_close()\ncalls are not longer fulfilling the offset and size checks. This leads to\nreference count leaks.\n\nAs perf already has the requirement for subsequent mappings to match the\ninitial mapping, the obvious consequence is that VMA splits, caused by\nresizing of a mapping or partial unmapping, have to be prevented.\n\nImplement the vm_operations_struct::may_split() callback and return\nunconditionally -EINVAL.\n\nThat ensures that the mapping offsets and sizes cannot be changed after the\nfact. Remapping to a different fixed address with the same size is still\npossible as it takes the references for the new mapping and drops those of\nthe old mapping.",
  "id": "GHSA-722p-jvv6-w5fv",
  "modified": "2025-08-28T15:30:38Z",
  "published": "2025-08-19T18:31:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38563"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3bd518cc7ea61076bcd725e36ff0e690754977c0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/65311aad4c808bedad0c05d9bb8b06c47dae73eb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6757a31a8e295ae4f01717a954afda173f25a121"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7b84cb58d1f0aa07656802eae24689566e5f5b1b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b024d7b56c77191cde544f838debb7f8451cd0d6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d52451a9210f2e5a079ba052918c93563518a9ff"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e4346ffec2c44d6b0be834d59b20632b5bb5729e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e529888b7e8092912dd8789bdfc76685ccd2ff5f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ff668930871e0198c7f4e325058b8b7c286787bd"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.