---
id: CVE-2026-64034
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer

  In mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from
  DMA-coherent memory and bounds-…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer

  In mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from
  DMA-coherent memory and bounds-…
severity: critical
cvss: 9.3
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H'
cwe:
  - CWE-367
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.13, < 5.15.209'
  - 'linux_kernel >= 5.16, < 6.1.175'
  - 'linux_kernel >= 6.2, < 6.6.142'
  - 'linux_kernel >= 6.7, < 6.12.92'
  - 'linux_kernel >= 6.13, < 6.18.34'
  - 'linux_kernel >= 6.19, < 7.0.11'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.11
published: '2026-07-19'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T15:30:25.333'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64034'
references:
  - url: 'https://git.kernel.org/stable/c/09ec063d87c2dd3fa6f3561361a017bd882e9f37'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/35f0f0a2536a4d604b4dbad92c85c4a8fdebb870'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/3c4db56ccd13dd020fbf43afabaee74a40ec75e4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/566f42fb67a7ebfed6650e407e5b72e6b3e83bf7'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/6180a06bbc99fd9114b8db4be6c4d46e40f046ef'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/70ad2dff8d052a85dfef15715b531f38a29108cf'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a201c66edf2ebc6cfdc3813a889ba20fecebfae3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00149
epssPercentile: 0.03624
ingestedAt: '2026-10-13T15:33:40.028Z'
---

## Overview

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

net: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer

In mana_hwc_rx_event_handler(), resp->response.hwc_msg_id is read from
DMA-coherent memory and bounds-checked, then mana_hwc_handle_resp()
re-reads the same field from the same DMA buffer for test_bit() and
pointer arithmetic.

DMA-coherent memory is mapped uncacheable on x86 and is shared,
unencrypted, in Confidential VMs (SEV-SNP/TDX), so each load goes
directly to host-visible memory. A H/W can modify the value
between the check and the use, bypassing the bounds validation.

Fix this by reading hwc_msg_id exactly once using READ_ONCE() into a
stack-local variable in mana_hwc_rx_event_handler(), and passing the
validated value as a parameter to mana_hwc_handle_resp().

## Affected

- `linux_kernel >= 5.13, < 5.15.209`
- `linux_kernel >= 5.16, < 6.1.175`
- `linux_kernel >= 6.2, < 6.6.142`
- `linux_kernel >= 6.7, < 6.12.92`
- `linux_kernel >= 6.13, < 6.18.34`
- `linux_kernel >= 6.19, < 7.0.11`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.11`