GHSA-2648-XH5W-2W3Q
Vulnerability from github – Published: 2025-04-03 09:32 – Updated: 2025-04-10 18:32In the Linux kernel, the following vulnerability has been resolved:
can: ucan: fix out of bound read in strscpy() source
Commit 7fdaf8966aae ("can: ucan: use strscpy() to instead of strncpy()") unintentionally introduced a one byte out of bound read on strscpy()'s source argument (which is kind of ironic knowing that strscpy() is meant to be a more secure alternative :)).
Let's consider below buffers:
dest[len + 1]; / will be NUL terminated / src[len]; / may not be NUL terminated /
When doing:
strncpy(dest, src, len); dest[len] = '\0';
strncpy() will read up to len bytes from src.
On the other hand:
strscpy(dest, src, len + 1);
will read up to len + 1 bytes from src, that is to say, an out of bound read of one byte will occur on src if it is not NUL terminated. Note that the src[len] byte is never copied, but strscpy() still needs to read it to check whether a truncation occurred or not.
This exact pattern happened in ucan.
The root cause is that the source is not NUL terminated. Instead of doing a copy in a local buffer, directly NUL terminate it as soon as usb_control_msg() returns. With this, the local firmware_str[] variable can be removed.
On top of this do a couple refactors:
-
ucan_ctl_payload->raw is only used for the firmware string, so rename it to ucan_ctl_payload->fw_str and change its type from u8 to char.
-
ucan_device_request_in() is only used to retrieve the firmware string, so rename it to ucan_get_fw_str() and refactor it to make it directly handle all the string termination logic.
{
"affected": [],
"aliases": [
"CVE-2025-22003"
],
"database_specific": {
"cwe_ids": [
"CWE-125"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-03T08:15:15Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: ucan: fix out of bound read in strscpy() source\n\nCommit 7fdaf8966aae (\"can: ucan: use strscpy() to instead of strncpy()\")\nunintentionally introduced a one byte out of bound read on strscpy()\u0027s\nsource argument (which is kind of ironic knowing that strscpy() is meant\nto be a more secure alternative :)).\n\nLet\u0027s consider below buffers:\n\n dest[len + 1]; /* will be NUL terminated */\n src[len]; /* may not be NUL terminated */\n\nWhen doing:\n\n strncpy(dest, src, len);\n dest[len] = \u0027\\0\u0027;\n\nstrncpy() will read up to len bytes from src.\n\nOn the other hand:\n\n strscpy(dest, src, len + 1);\n\nwill read up to len + 1 bytes from src, that is to say, an out of bound\nread of one byte will occur on src if it is not NUL terminated. Note\nthat the src[len] byte is never copied, but strscpy() still needs to\nread it to check whether a truncation occurred or not.\n\nThis exact pattern happened in ucan.\n\nThe root cause is that the source is not NUL terminated. Instead of\ndoing a copy in a local buffer, directly NUL terminate it as soon as\nusb_control_msg() returns. With this, the local firmware_str[] variable\ncan be removed.\n\nOn top of this do a couple refactors:\n\n - ucan_ctl_payload-\u003eraw is only used for the firmware string, so\n rename it to ucan_ctl_payload-\u003efw_str and change its type from u8 to\n char.\n\n - ucan_device_request_in() is only used to retrieve the firmware\n string, so rename it to ucan_get_fw_str() and refactor it to make it\n directly handle all the string termination logic.",
"id": "GHSA-2648-xh5w-2w3q",
"modified": "2025-04-10T18:32:02Z",
"published": "2025-04-03T09:32:15Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-22003"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1d22a122ffb116c3cf78053e812b8b21f8852ee9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8cec9e314d3360fc1d8346297c41a6ee45cb45a9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a4994161a61bc8fd71d105c579d847cefee99262"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cc29775a8a72d7f3b56cc026796ad99bd65804a7"
}
],
"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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