GHSA-J555-7G4R-X4W9

Vulnerability from github – Published: 2025-10-15 09:30 – Updated: 2026-07-30 06:32
VLAI
Details

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

can: hi311x: populate ndo_change_mtu() to prevent buffer overflow

Sending an PF_PACKET allows to bypass the CAN framework logic and to directly reach the xmit() function of a CAN driver. The only check which is performed by the PF_PACKET framework is to make sure that skb->len fits the interface's MTU.

Unfortunately, because the sun4i_can driver does not populate its net_device_ops->ndo_change_mtu(), it is possible for an attacker to configure an invalid MTU by doing, for example:

$ ip link set can0 mtu 9999

After doing so, the attacker could open a PF_PACKET socket using the ETH_P_CANXL protocol:

socket(PF_PACKET, SOCK_RAW, htons(ETH_P_CANXL))

to inject a malicious CAN XL frames. For example:

struct canxl_frame frame = {
    .flags = 0xff,
    .len = 2048,
};

The CAN drivers' xmit() function are calling can_dev_dropped_skb() to check that the skb is valid, unfortunately under above conditions, the malicious packet is able to go through can_dev_dropped_skb() checks:

  1. the skb->protocol is set to ETH_P_CANXL which is valid (the function does not check the actual device capabilities).

  2. the length is a valid CAN XL length.

And so, hi3110_hard_start_xmit() receives a CAN XL frame which it is not able to correctly handle and will thus misinterpret it as a CAN frame. The driver will consume frame->len as-is with no further checks.

This can result in a buffer overflow later on in hi3110_hw_tx() on this line:

memcpy(buf + HI3110_FIFO_EXT_DATA_OFF,
       frame->data, frame->len);

Here, frame->len corresponds to the flags field of the CAN XL frame. In our previous example, we set canxl_frame->flags to 0xff. Because the maximum expected length is 8, a buffer overflow of 247 bytes occurs!

Populate net_device_ops->ndo_change_mtu() to ensure that the interface's MTU can not be set to anything bigger than CAN_MTU. By fixing the root cause, this prevents the buffer overflow.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Show details on source website
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{
  "affected": [],
  "aliases": [
    "CVE-2025-39987"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-10-15T08:15:36Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: hi311x: populate ndo_change_mtu() to prevent buffer overflow\n\nSending an PF_PACKET allows to bypass the CAN framework logic and to\ndirectly reach the xmit() function of a CAN driver. The only check\nwhich is performed by the PF_PACKET framework is to make sure that\nskb-\u003elen fits the interface\u0027s MTU.\n\nUnfortunately, because the sun4i_can driver does not populate its\nnet_device_ops-\u003endo_change_mtu(), it is possible for an attacker to\nconfigure an invalid MTU by doing, for example:\n\n  $ ip link set can0 mtu 9999\n\nAfter doing so, the attacker could open a PF_PACKET socket using the\nETH_P_CANXL protocol:\n\n\tsocket(PF_PACKET, SOCK_RAW, htons(ETH_P_CANXL))\n\nto inject a malicious CAN XL frames. For example:\n\n\tstruct canxl_frame frame = {\n\t\t.flags = 0xff,\n\t\t.len = 2048,\n\t};\n\nThe CAN drivers\u0027 xmit() function are calling can_dev_dropped_skb() to\ncheck that the skb is valid, unfortunately under above conditions, the\nmalicious packet is able to go through can_dev_dropped_skb() checks:\n\n  1. the skb-\u003eprotocol is set to ETH_P_CANXL which is valid (the\n     function does not check the actual device capabilities).\n\n  2. the length is a valid CAN XL length.\n\nAnd so, hi3110_hard_start_xmit() receives a CAN XL frame which it is\nnot able to correctly handle and will thus misinterpret it as a CAN\nframe. The driver will consume frame-\u003elen as-is with no further\nchecks.\n\nThis can result in a buffer overflow later on in hi3110_hw_tx() on\nthis line:\n\n\tmemcpy(buf + HI3110_FIFO_EXT_DATA_OFF,\n\t       frame-\u003edata, frame-\u003elen);\n\nHere, frame-\u003elen corresponds to the flags field of the CAN XL frame.\nIn our previous example, we set canxl_frame-\u003eflags to 0xff. Because\nthe maximum expected length is 8, a buffer overflow of 247 bytes\noccurs!\n\nPopulate net_device_ops-\u003endo_change_mtu() to ensure that the\ninterface\u0027s MTU can not be set to anything bigger than CAN_MTU. By\nfixing the root cause, this prevents the buffer overflow.",
  "id": "GHSA-j555-7g4r-x4w9",
  "modified": "2026-07-30T06:32:11Z",
  "published": "2025-10-15T09:30:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39987"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/57d332ce8c921d0e340650470bb0c1d707f216ee"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7ab85762274c0fa997f0ef9a2307b2001aae43c4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8f351db6b2367991f0736b2cff082f5de4872113"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ac1c7656fa717f29fac3ea073af63f0b9919ec9a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/be1b25005fd0f9d4e78bec6695711ef87ee33398"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/def814b4ba31b563584061d6895d5ff447d5bc14"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e77fdf9e33a83a08f04ab0cb68c19ddb365a622f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f2c247e9581024d8b3dd44cbe086bf2bebbef42c"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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