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dmaengine: Fix device kref underflow in dma_chan_put()

Type: advisorySources: OSV

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.

Products
Kernel
Affected versions
Not specified
Fixed versions
5.10.271, 5.15.222, 6.1.189, 6.12.112, 6.18.54, 6.6.158, 7.2.8
CVEs
CVE-2026-98344
Confirmed fixed CVEs
Not specified
Updated in this feed
2 Nov 2026, 16:47 UTC · Revision 1

Source evidence

dmaengine: Fix device kref underflow in dma_chan_put()

core-osv · Original source

Published 6 Oct 2026, 08:46 UTC

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.

osv:CVE-2026-98344

Kernel

Fixed versions: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.54, 7.2.8

Complete source record
{
  "id": "cf2862e6a79a65fee7f28e8c644116e4583ad535abea9a33aa7c4d02a3fae2b4",
  "url": "https://osv.dev/vulnerability/CVE-2026-98344",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "dmaengine: Fix device kref underflow in dma_chan_put()",
    "summary": "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.",
    "evidence": "osv:CVE-2026-98344",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.271",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.222",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.189",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.158",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.112",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.54",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98344",
      "aliases": [
        "CVE-2026-98344"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "fixed": "036b527f92570206da4b8c40b38f8d689e29d0f3"
                },
                {
                  "fixed": "5fb1797a8c9485e40e5492fa0338ab5c7d1f3fef"
                },
                {
                  "fixed": "57f7f1c6827be7d8f80feca48d2125fb91c6f6ed"
                },
                {
                  "fixed": "7c3f4ce651d43705f9ec7f778f642a90d5ff4fba"
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                {
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                {
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                  "fixed": "44dab659064eb5c10adb0306510eebe848ed592d"
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98344.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.6.0"
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                {
                  "fixed": "5.10.271"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
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                {
                  "fixed": "5.15.222"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.189"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.112"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
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                {
                  "fixed": "6.18.54"
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            },
            {
              "type": "ECOSYSTEM",
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                {
                  "introduced": "6.19.0"
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98344.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:21.081782680Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/036b527f92570206da4b8c40b38f8d689e29d0f3",
        "https://git.kernel.org/stable/c/1a0d9b406febf23054ad595fd47b29325e70fb2d",
        "https://git.kernel.org/stable/c/44dab659064eb5c10adb0306510eebe848ed592d",
        "https://git.kernel.org/stable/c/57f7f1c6827be7d8f80feca48d2125fb91c6f6ed",
        "https://git.kernel.org/stable/c/5fb1797a8c9485e40e5492fa0338ab5c7d1f3fef",
        "https://git.kernel.org/stable/c/77906ac448d2fa81fa710ae26c0e591ebdc81154",
        "https://git.kernel.org/stable/c/7c3f4ce651d43705f9ec7f778f642a90d5ff4fba",
        "https://git.kernel.org/stable/c/de2677e57d3161390d8a508f08cddec6ef7e4b23",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98344.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98344",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98344.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98344",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 487375,
  "published_at": "2026-10-06T08:46:33.997+00:00"
}