{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "3e26d9f08fbe0b73e951a5e810fdb7a332b7e37f"
            },
            {
              "fixed": "9678aeed8b77d495a417dd057d479f3733094019"
            },
            {
              "fixed": "3412a95afaa5d3262008dfc34f3c7be33d8151dc"
            },
            {
              "fixed": "96cdeaba6a008503455b78a9641c05c2a886a7ec"
            },
            {
              "fixed": "a093999355084bdbfe6e97f1dd232e58a1525f0b"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.11.0"
            },
            {
              "fixed": "6.12.93"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.35"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.0.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63929.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\niio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()\n\niio_buffer_enqueue_dmabuf() allocates a struct iio_dma_fence (104 bytes,\nkmalloc-128) via kmalloc_obj()+dma_fence_init(), which sets the initial\nkref to 1.  It then calls dma_resv_add_fence() which takes a second\nreference (kref=2), and stores a raw pointer in block-\u003efence.\n\nOn the success path the function returns without calling dma_fence_put()\nto release the initial reference, so every buffer enqueue permanently\nleaks one kmalloc-128 allocation.\n\nThe iio_buffer_cleanup() work item only releases the temporary reference\ntaken during completion signalling by iio_buffer_signal_dmabuf_done();\nthe initial reference from dma_fence_init() is never released.\n\nWith four iio_rwdev instances at 240kHz and 512 samples per buffer,\nthis produces ~1875 kmalloc-128 allocations per second matching the\nobserved slab growth exactly. A test with ftrace confirmed that the\ndma_fence_destroy event was never triggered.\n\nFix by calling dma_fence_put() after dma_resv_add_fence(), transferring\nownership of the fence to the DMA reservation object. The DMA fence then\ngets properly discarded after being signalled.",
  "id": "CVE-2026-63929",
  "modified": "2026-08-12T03:51:43.973408732Z",
  "published": "2026-07-19T14:55:29.309Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3412a95afaa5d3262008dfc34f3c7be33d8151dc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9678aeed8b77d495a417dd057d479f3733094019"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/96cdeaba6a008503455b78a9641c05c2a886a7ec"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a093999355084bdbfe6e97f1dd232e58a1525f0b"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63929.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63929"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "iio: buffer: Fix DMA fence leak in iio_buffer_enqueue_dmabuf()"
}