ghsa-gcgx-pvvc-73xm
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
hwmon: (ftsteutates) Fix TOCTOU race in fts_read()
In the fts_read() function, when handling hwmon_pwm_auto_channels_temp, the code accesses the shared variable data->fan_source[channel] twice without holding any locks. It is first checked against FTS_FAN_SOURCE_INVALID, and if the check passes, it is read again when used as an argument to the BIT() macro.
This creates a Time-of-Check to Time-of-Use (TOCTOU) race condition. Another thread executing fts_update_device() can modify the value of data->fan_source[channel] between the check and its use. If the value is changed to FTS_FAN_SOURCE_INVALID (0xff) during this window, the BIT() macro will be called with a large shift value (BIT(255)). A bit shift by a value greater than or equal to the type width is undefined behavior and can lead to a crash or incorrect values being returned to userspace.
Fix this by reading data->fan_source[channel] into a local variable once, eliminating the race condition. Additionally, add a bounds check to ensure the value is less than BITS_PER_LONG before passing it to the BIT() macro, making the code more robust against undefined behavior.
This possible bug was found by an experimental static analysis tool developed by our team.
{
"affected": [],
"aliases": [
"CVE-2025-38217"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-07-04T14:15:30Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nhwmon: (ftsteutates) Fix TOCTOU race in fts_read()\n\nIn the fts_read() function, when handling hwmon_pwm_auto_channels_temp,\nthe code accesses the shared variable data-\u003efan_source[channel] twice\nwithout holding any locks. It is first checked against\nFTS_FAN_SOURCE_INVALID, and if the check passes, it is read again\nwhen used as an argument to the BIT() macro.\n\nThis creates a Time-of-Check to Time-of-Use (TOCTOU) race condition.\nAnother thread executing fts_update_device() can modify the value of\ndata-\u003efan_source[channel] between the check and its use. If the value\nis changed to FTS_FAN_SOURCE_INVALID (0xff) during this window, the\nBIT() macro will be called with a large shift value (BIT(255)).\nA bit shift by a value greater than or equal to the type width is\nundefined behavior and can lead to a crash or incorrect values being\nreturned to userspace.\n\nFix this by reading data-\u003efan_source[channel] into a local variable\nonce, eliminating the race condition. Additionally, add a bounds check\nto ensure the value is less than BITS_PER_LONG before passing it to\nthe BIT() macro, making the code more robust against undefined behavior.\n\nThis possible bug was found by an experimental static analysis tool\ndeveloped by our team.",
"id": "GHSA-gcgx-pvvc-73xm",
"modified": "2025-07-04T15:31:09Z",
"published": "2025-07-04T15:31:09Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38217"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/14c9ede9ca4cd078ad76a6ab9617b81074eb58bf"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4d646f627d3b7ed1cacca66e598af8bcd632d465"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/83e2ba8971ccd8fc08319fc7593288f070d80a76"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d95d87841d2a575bed3691884e8fedef57d7710d"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
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- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.