GHSA-R5HJ-4CHX-57CX

Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-20 15:31
VLAI
Details

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().

Severity
9.3 (Critical)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64034"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T16:17:43Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: mana: Fix TOCTOU double-fetch of hwc_msg_id from DMA buffer\n\nIn mana_hwc_rx_event_handler(), resp-\u003eresponse.hwc_msg_id is read from\nDMA-coherent memory and bounds-checked, then mana_hwc_handle_resp()\nre-reads the same field from the same DMA buffer for test_bit() and\npointer arithmetic.\n\nDMA-coherent memory is mapped uncacheable on x86 and is shared,\nunencrypted, in Confidential VMs (SEV-SNP/TDX), so each load goes\ndirectly to host-visible memory. A H/W can modify the value\nbetween the check and the use, bypassing the bounds validation.\n\nFix this by reading hwc_msg_id exactly once using READ_ONCE() into a\nstack-local variable in mana_hwc_rx_event_handler(), and passing the\nvalidated value as a parameter to mana_hwc_handle_resp().",
  "id": "GHSA-r5hj-4chx-57cx",
  "modified": "2026-07-20T15:31:56Z",
  "published": "2026-07-19T18:31:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64034"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/09ec063d87c2dd3fa6f3561361a017bd882e9f37"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/35f0f0a2536a4d604b4dbad92c85c4a8fdebb870"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3c4db56ccd13dd020fbf43afabaee74a40ec75e4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/566f42fb67a7ebfed6650e407e5b72e6b3e83bf7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6180a06bbc99fd9114b8db4be6c4d46e40f046ef"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/70ad2dff8d052a85dfef15715b531f38a29108cf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a201c66edf2ebc6cfdc3813a889ba20fecebfae3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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