GHSA-P5PR-V4M5-R2VJ

Vulnerability from github – Published: 2025-12-23 15:30 – Updated: 2025-12-23 15:30
VLAI?
Details

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

atm/fore200e: Fix possible data race in fore200e_open()

Protect access to fore200e->available_cell_rate with rate_mtx lock in the error handling path of fore200e_open() to prevent a data race.

The field fore200e->available_cell_rate is a shared resource used to track available bandwidth. It is concurrently accessed by fore200e_open(), fore200e_close(), and fore200e_change_qos().

In fore200e_open(), the lock rate_mtx is correctly held when subtracting vcc->qos.txtp.max_pcr from available_cell_rate to reserve bandwidth. However, if the subsequent call to fore200e_activate_vcin() fails, the function restores the reserved bandwidth by adding back to available_cell_rate without holding the lock.

This introduces a race condition because available_cell_rate is a global device resource shared across all VCCs. If the error path in fore200e_open() executes concurrently with operations like fore200e_close() or fore200e_change_qos() on other VCCs, a read-modify-write race occurs.

Specifically, the error path reads the rate without the lock. If another CPU acquires the lock and modifies the rate (e.g., releasing bandwidth in fore200e_close()) between this read and the subsequent write, the error path will overwrite the concurrent update with a stale value. This results in incorrect bandwidth accounting.

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{
  "affected": [],
  "aliases": [
    "CVE-2025-68339"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-12-23T14:16:40Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\natm/fore200e: Fix possible data race in fore200e_open()\n\nProtect access to fore200e-\u003eavailable_cell_rate with rate_mtx lock in the\nerror handling path of fore200e_open() to prevent a data race.\n\nThe field fore200e-\u003eavailable_cell_rate is a shared resource used to track\navailable bandwidth. It is concurrently accessed by fore200e_open(),\nfore200e_close(), and fore200e_change_qos().\n\nIn fore200e_open(), the lock rate_mtx is correctly held when subtracting\nvcc-\u003eqos.txtp.max_pcr from available_cell_rate to reserve bandwidth.\nHowever, if the subsequent call to fore200e_activate_vcin() fails, the\nfunction restores the reserved bandwidth by adding back to\navailable_cell_rate without holding the lock.\n\nThis introduces a race condition because available_cell_rate is a global\ndevice resource shared across all VCCs. If the error path in\nfore200e_open() executes concurrently with operations like\nfore200e_close() or fore200e_change_qos() on other VCCs, a\nread-modify-write race occurs.\n\nSpecifically, the error path reads the rate without the lock. If another\nCPU acquires the lock and modifies the rate (e.g., releasing bandwidth in\nfore200e_close()) between this read and the subsequent write, the error\npath will overwrite the concurrent update with a stale value. This results\nin incorrect bandwidth accounting.",
  "id": "GHSA-p5pr-v4m5-r2vj",
  "modified": "2025-12-23T15:30:40Z",
  "published": "2025-12-23T15:30:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-68339"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1b60f42a639999c37da7f1fbfa1ad29cf4cbdd2d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6610361458e7eb6502dd3182f586f91fcc218039"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/667ac868823224374f819500adc5baa2889c7bc5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/82fca3d8a4a34667f01ec2351a607135249c9cff"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9917ba597cf95f307778e495f71ff25a5064d167"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bd1415efbab507b9b995918105eef953013449dd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ed34c70d88e2b8b9bc6c3ede88751186d6c6d5d1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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