GHSA-5Q82-R42M-G49M

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: etas_es58x: 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 etas_es58x 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, es58x_start_xmit() receives a CAN XL frame which it is not able to correctly handle and will thus misinterpret it as a CAN(FD) frame.

This can result in a buffer overflow. For example, using the es581.4 variant, the frame will be dispatched to es581_4_tx_can_msg(), go through the last check at the beginning of this function:

if (can_is_canfd_skb(skb))
    return -EMSGSIZE;

and reach this line:

memcpy(tx_can_msg->data, cf->data, cf->len);

Here, cf->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 or CANFD_MTU (depending on the device capabilities). 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
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{
  "affected": [],
  "aliases": [
    "CVE-2025-39988"
  ],
  "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: etas_es58x: 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 etas_es58x 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, es58x_start_xmit() receives a CAN XL frame which it is not\nable to correctly handle and will thus misinterpret it as a CAN(FD)\nframe.\n\nThis can result in a buffer overflow. For example, using the es581.4\nvariant, the frame will be dispatched to es581_4_tx_can_msg(), go\nthrough the last check at the beginning of this function:\n\n\tif (can_is_canfd_skb(skb))\n\t\treturn -EMSGSIZE;\n\nand reach this line:\n\n\tmemcpy(tx_can_msg-\u003edata, cf-\u003edata, cf-\u003elen);\n\nHere, cf-\u003elen corresponds to the flags field of the CAN XL frame. In\nour previous example, we set canxl_frame-\u003eflags to 0xff. Because the\nmaximum expected length is 8, a buffer overflow of 247 bytes occurs!\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 or\nCANFD_MTU (depending on the device capabilities). By fixing the root\ncause, this prevents the buffer overflow.",
  "id": "GHSA-5q82-r42m-g49m",
  "modified": "2026-07-30T06:32:11Z",
  "published": "2025-10-15T09:30:17Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39988"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/38c0abad45b190a30d8284a37264d2127a6ec303"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/72de0facc50afdb101fb7197d880407f1abfc77f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b26cccd87dcddc47b450a40f3b1ac3fe346efcff"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c4e582e686c4d683c87f2b4a316385b3d81d370f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cbc1de71766f326a44bb798aeae4a7ef4a081cc9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e587af2c89ecc6382c518febea52fa9ba81e47c0"
    }
  ],
  "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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