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GHSA-G37W-WJP2-MP83

Vulnerability from github – Published: 2024-05-19 12:30 – Updated: 2026-05-12 12:31
VLAI
Details

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

VMCI: Fix memcpy() run-time warning in dg_dispatch_as_host()

Syzkaller hit 'WARNING in dg_dispatch_as_host' bug.

memcpy: detected field-spanning write (size 56) of single field "&dg_info->msg" at drivers/misc/vmw_vmci/vmci_datagram.c:237 (size 24)

WARNING: CPU: 0 PID: 1555 at drivers/misc/vmw_vmci/vmci_datagram.c:237 dg_dispatch_as_host+0x88e/0xa60 drivers/misc/vmw_vmci/vmci_datagram.c:237

Some code commentry, based on my understanding:

544 #define VMCI_DG_SIZE(_dg) (VMCI_DG_HEADERSIZE + (size_t)(_dg)->payload_size) /// This is 24 + payload_size

memcpy(&dg_info->msg, dg, dg_size); Destination = dg_info->msg ---> this is a 24 byte structure(struct vmci_datagram) Source = dg --> this is a 24 byte structure (struct vmci_datagram) Size = dg_size = 24 + payload_size

{payload_size = 56-24 =32} -- Syzkaller managed to set payload_size to 32.

35 struct delayed_datagram_info { 36 struct datagram_entry entry; 37 struct work_struct work; 38 bool in_dg_host_queue; 39 / msg and msg_payload must be together. */ 40 struct vmci_datagram msg; 41 u8 msg_payload[]; 42 };

So those extra bytes of payload are copied into msg_payload[], a run time warning is seen while fuzzing with Syzkaller.

One possible way to fix the warning is to split the memcpy() into two parts -- one -- direct assignment of msg and second taking care of payload.

Gustavo quoted: "Under FORTIFY_SOURCE we should not copy data across multiple members in a structure."

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2024-35944"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-05-19T11:15:50Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nVMCI: Fix memcpy() run-time warning in dg_dispatch_as_host()\n\nSyzkaller hit \u0027WARNING in dg_dispatch_as_host\u0027 bug.\n\nmemcpy: detected field-spanning write (size 56) of single field \"\u0026dg_info-\u003emsg\"\nat drivers/misc/vmw_vmci/vmci_datagram.c:237 (size 24)\n\nWARNING: CPU: 0 PID: 1555 at drivers/misc/vmw_vmci/vmci_datagram.c:237\ndg_dispatch_as_host+0x88e/0xa60 drivers/misc/vmw_vmci/vmci_datagram.c:237\n\nSome code commentry, based on my understanding:\n\n544 #define VMCI_DG_SIZE(_dg) (VMCI_DG_HEADERSIZE + (size_t)(_dg)-\u003epayload_size)\n/// This is 24 + payload_size\n\nmemcpy(\u0026dg_info-\u003emsg, dg, dg_size);\n\tDestination = dg_info-\u003emsg ---\u003e this is a 24 byte\n\t\t\t\t\tstructure(struct vmci_datagram)\n\tSource = dg --\u003e this is a 24 byte structure (struct vmci_datagram)\n\tSize = dg_size = 24 + payload_size\n\n{payload_size = 56-24 =32} -- Syzkaller managed to set payload_size to 32.\n\n 35 struct delayed_datagram_info {\n 36         struct datagram_entry *entry;\n 37         struct work_struct work;\n 38         bool in_dg_host_queue;\n 39         /* msg and msg_payload must be together. */\n 40         struct vmci_datagram msg;\n 41         u8 msg_payload[];\n 42 };\n\nSo those extra bytes of payload are copied into msg_payload[], a run time\nwarning is seen while fuzzing with Syzkaller.\n\nOne possible way to fix the warning is to split the memcpy() into\ntwo parts -- one -- direct assignment of msg and second taking care of payload.\n\nGustavo quoted:\n\"Under FORTIFY_SOURCE we should not copy data across multiple members\nin a structure.\"",
  "id": "GHSA-g37w-wjp2-mp83",
  "modified": "2026-05-12T12:31:50Z",
  "published": "2024-05-19T12:30:39Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35944"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-265688.html"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-398330.html"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/130b0cd064874e0d0f58e18fb00e6f3993e90c74"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/19b070fefd0d024af3daa7329cbc0d00de5302ec"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/491a1eb07c2bd8841d63cb5263455e185be5866f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ad78c5047dc4076d0b3c4fad4f42ffe9c86e8100"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dae70a57565686f16089737adb8ac64471570f73"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e87bb99d2df6512d8ee37a5d63d2ca9a39a8c051"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f15eca95138b3d4ec17b63c3c1937b0aa0d3624b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/feacd430b42bbfa9ab3ed9e4f38b86c43e348c75"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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