GHSA-4P2M-H7J8-HHXJ

Vulnerability from github – Published: 2026-05-27 15:33 – Updated: 2026-05-27 15:33
VLAI
Details

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

ibmasm: fix heap over-read in ibmasm_send_i2o_message()

The ibmasm_send_i2o_message() function uses get_dot_command_size() to compute the byte count for memcpy_toio(), but this value is derived from user-controlled fields in the dot_command_header (command_size: u8, data_size: u16) and is never validated against the actual allocation size. A root user can write a small buffer with inflated header fields, causing memcpy_toio() to read up to ~65 KB past the end of the allocation into adjacent kernel heap, which is then forwarded to the service processor over MMIO.

Silently clamping the copy size is not sufficient: if the header fields claim a larger size than the buffer, the SP receives a dot command whose own header is inconsistent with the I2O message length, which can cause the SP to desynchronize. Reject such commands outright by returning failure.

Validate command_size before calling get_mfa_inbound() to avoid leaking an I2O message frame: reading INBOUND_QUEUE_PORT dequeues a hardware frame from the controller's free pool, and returning without a corresponding set_mfa_inbound() call would permanently exhaust it.

Additionally, clamp command_size to I2O_COMMAND_SIZE before the memcpy_toio() so the MMIO write stays within the I2O message frame, consistent with the clamping already performed by outgoing_message_size() for the header field.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-46064"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-27T14:17:26Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nibmasm: fix heap over-read in ibmasm_send_i2o_message()\n\nThe ibmasm_send_i2o_message() function uses get_dot_command_size() to\ncompute the byte count for memcpy_toio(), but this value is derived from\nuser-controlled fields in the dot_command_header (command_size: u8,\ndata_size: u16) and is never validated against the actual allocation size.\nA root user can write a small buffer with inflated header fields, causing\nmemcpy_toio() to read up to ~65 KB past the end of the allocation into\nadjacent kernel heap, which is then forwarded to the service processor\nover MMIO.\n\nSilently clamping the copy size is not sufficient: if the header fields\nclaim a larger size than the buffer, the SP receives a dot command whose\nown header is inconsistent with the I2O message length, which can cause\nthe SP to desynchronize. Reject such commands outright by returning\nfailure.\n\nValidate command_size before calling get_mfa_inbound() to avoid leaking\nan I2O message frame: reading INBOUND_QUEUE_PORT dequeues a hardware\nframe from the controller\u0027s free pool, and returning without a\ncorresponding set_mfa_inbound() call would permanently exhaust it.\n\nAdditionally, clamp command_size to I2O_COMMAND_SIZE before the\nmemcpy_toio() so the MMIO write stays within the I2O message frame,\nconsistent with the clamping already performed by outgoing_message_size()\nfor the header field.",
  "id": "GHSA-4p2m-h7j8-hhxj",
  "modified": "2026-05-27T15:33:23Z",
  "published": "2026-05-27T15:33:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46064"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9aad71144fa3682cca3837a06c8623016790e7ec"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9e8f6c9d4ecddda2f28baa1678340286cff3969c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c1c2417c60dbdca5ebb00462f21ee71c2d7f7083"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fd19eb1c75047a4ed4e855f56cafd704dc3914e0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fe31722b0194ff76bf8b461e8bf97a2081147787"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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