GHSA-G4C2-FM3R-X4GH

Vulnerability from github – Published: 2026-10-06 09:31 – Updated: 2026-10-06 09:31
VLAI
Details

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

dmaengine: Fix device kref underflow in dma_chan_put()

dma_chan_get() takes chan->device->ref only on the slow path:

/* no kref on fast path */
if (chan->client_count) {
    __module_get(owner);
    chan->client_count++;
    return 0;
}
if (!try_module_get(owner))
    return -ENODEV;
if (!dma_device_get(chan->device)) { // calls kref_get_unless_zero()

dma_chan_put() drops the ref unconditionally, so every fast-path get/put pair drops one extra device reference.

The bug fires when two conditions hold together: a non-private provider has a persistent client holding chan->client_count > 0 and another client cycles dmaengine_get()/dmaengine_put(). When the kref hits zero, the subsequent dma_find_channel() returns NULL even though the provider module is still loaded.

Fix this by dropping device->ref only on the last put, matching the single slow-path get.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98344"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-06T09:18:27Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ndmaengine: Fix device kref underflow in dma_chan_put()\n\ndma_chan_get() takes chan-\u003edevice-\u003eref only on the slow path:\n\n\t/* no kref on fast path */\n\tif (chan-\u003eclient_count) {\n\t\t__module_get(owner);\n\t\tchan-\u003eclient_count++;\n\t\treturn 0;\n\t}\n\tif (!try_module_get(owner))\n\t\treturn -ENODEV;\n\tif (!dma_device_get(chan-\u003edevice)) { // calls kref_get_unless_zero()\n\ndma_chan_put() drops the ref unconditionally, so every fast-path\nget/put pair drops one extra device reference.\n\nThe bug fires when two conditions hold together: a non-private\nprovider has a persistent client holding chan-\u003eclient_count \u003e 0\nand another client cycles dmaengine_get()/dmaengine_put().\nWhen the kref hits zero, the subsequent dma_find_channel() returns\nNULL even though the provider module is still loaded.\n\nFix this by dropping device-\u003eref only on the last put, matching the\nsingle slow-path get.",
  "id": "GHSA-g4c2-fm3r-x4gh",
  "modified": "2026-10-06T09:31:36Z",
  "published": "2026-10-06T09:31:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98344"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/036b527f92570206da4b8c40b38f8d689e29d0f3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1a0d9b406febf23054ad595fd47b29325e70fb2d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/44dab659064eb5c10adb0306510eebe848ed592d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/57f7f1c6827be7d8f80feca48d2125fb91c6f6ed"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5fb1797a8c9485e40e5492fa0338ab5c7d1f3fef"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/77906ac448d2fa81fa710ae26c0e591ebdc81154"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7c3f4ce651d43705f9ec7f778f642a90d5ff4fba"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/de2677e57d3161390d8a508f08cddec6ef7e4b23"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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