---
id: CVE-2026-46064
title: |-
  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(),…
summary: |-
  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(),…
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H'
cwe:
  - CWE-125
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 2.6.12.1, < 5.10.258'
  - 'linux_kernel >= 5.11, < 5.15.209'
  - 'linux_kernel >= 5.16, < 6.1.175'
  - 'linux_kernel >= 6.2, < 6.6.140'
  - 'linux_kernel >= 6.7, < 6.12.86'
  - 'linux_kernel >= 6.13, < 6.18.27'
  - 'linux_kernel >= 6.19, < 7.0.4'
  - linux_kernel = 2.6.12
patched:
  - linux_kernel 7.0.4
published: '2026-05-27'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T02:19:41.027'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-46064'
references:
  - url: 'https://git.kernel.org/stable/c/9aad71144fa3682cca3837a06c8623016790e7ec'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9e8f6c9d4ecddda2f28baa1678340286cff3969c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b870f652877bfbe321bd0f4096fc37a93296f7b6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c1c2417c60dbdca5ebb00462f21ee71c2d7f7083'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ca1c857e2bb74a9fc0606128334f85316d57067b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ce57fa439bd1b5d664f334a0c3e3f0e42abb0153'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fd19eb1c75047a4ed4e855f56cafd704dc3914e0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fe31722b0194ff76bf8b461e8bf97a2081147787'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-784472.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
  - cve.org
epss: 0.00167
epssPercentile: 0.05522
ingestedAt: '2026-10-15T03:30:12.884Z'
---

## Overview

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.

## Affected

- `linux_kernel >= 2.6.12.1, < 5.10.258`
- `linux_kernel >= 5.11, < 5.15.209`
- `linux_kernel >= 5.16, < 6.1.175`
- `linux_kernel >= 6.2, < 6.6.140`
- `linux_kernel >= 6.7, < 6.12.86`
- `linux_kernel >= 6.13, < 6.18.27`
- `linux_kernel >= 6.19, < 7.0.4`
- `linux_kernel = 2.6.12`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.4`