CVE-2026-63910 (GCVE-0-2026-63910)
Vulnerability from cvelistv5
Published
2026-07-19 14:55
Modified
2026-08-05 12:37
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: dma-buf: fix UAF in dma_buf_fd() tracepoint Once FD_ADD() returns, the fd is live in the file descriptor table and a thread sharing that table can close() it before DMA_BUF_TRACE() runs. The close drops the last reference, __fput() frees the dma_buf, and the tracepoint then dereferences dmabuf to take dmabuf->name_lock -- slab-use-after-free. Split FD_ADD() back into get_unused_fd_flags() + fd_install() and emit the tracepoint between them. While the fdtable slot is reserved with a NULL file pointer, a racing close() returns -EBADF without entering __fput(), so the dma_buf stays alive across the trace. Same approach as commit 2d76319c4cbb ("dma-buf: fix UAF in dma_buf_put() tracepoint"). This undoes the FD_ADD() conversion done in commit 34dfce523c90 ("dma: convert dma_buf_fd() to FD_ADD()"); FD_ADD() has no place to hook the tracepoint safely.
References
Impacted products
Vendor Product Version
Linux Linux Version: 281a226314238e8adb08d11b765347687ffb38b9
Version: 281a226314238e8adb08d11b765347687ffb38b9
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/dma-buf/dma-buf.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b569f86e2f8dbf6f11d31d3de794d22e18098b23",
              "status": "affected",
              "version": "281a226314238e8adb08d11b765347687ffb38b9",
              "versionType": "git"
            },
            {
              "lessThan": "ead6680f354f83966c796fc7f9463a3171789616",
              "status": "affected",
              "version": "281a226314238e8adb08d11b765347687ffb38b9",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/dma-buf/dma-buf.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.12",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndma-buf: fix UAF in dma_buf_fd() tracepoint\n\nOnce FD_ADD() returns, the fd is live in the file descriptor table\nand a thread sharing that table can close() it before DMA_BUF_TRACE()\nruns. The close drops the last reference, __fput() frees the dma_buf,\nand the tracepoint then dereferences dmabuf to take dmabuf-\u003ename_lock\n-- slab-use-after-free.\n\nSplit FD_ADD() back into get_unused_fd_flags() + fd_install() and\nemit the tracepoint between them. While the fdtable slot is reserved\nwith a NULL file pointer, a racing close() returns -EBADF without\nentering __fput(), so the dma_buf stays alive across the trace. Same\napproach as commit 2d76319c4cbb (\"dma-buf: fix UAF in dma_buf_put()\ntracepoint\").\n\nThis undoes the FD_ADD() conversion done in commit 34dfce523c90\n(\"dma: convert dma_buf_fd() to FD_ADD()\"); FD_ADD() has no place to\nhook the tracepoint safely."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The UAF is reached only through local syscalls/ioctls (e.g. UDMABUF_CREATE, DMA_HEAP_IOCTL_ALLOC, DRM/videobuf2 buffer export) that call dma_buf_fd(); there is no network or physical-device entry point.\nAC:L - Exploitation requires a race between dma_buf_fd() and close() on a shared fd table, but the attacker controls both threads and can hammer the window concurrently; syzkaller demonstrated reliable triggering without conditions outside attacker control.\nPR:L - An unprivileged local user with access to dma-buf interfaces (udmabuf, dma_heap, DRM render node, or media devices) can reach dma_buf_fd(); syzbot confirmed unprivileged and user-namespace reachability without real root in the init namespace.\nUI:N - Exploitation is performed entirely by the attacker\u0027s own multi-threaded process issuing ioctls and close() calls; no action by a separate victim user is required.\nS:U - Impact is kernel memory corruption and privilege escalation within the same kernel security domain; this is standard local kernel compromise, not a VM escape or IOMMU/DMA boundary bypass.\nC:H - The bug is a slab use-after-free on struct dma_buf; the tracepoint dereferences freed memory (name_lock, exp_name, file fields), enabling controlled reuse of freed kmalloc-1k objects for arbitrary kernel memory disclosure.\nI:H - UAF on a kmalloc-1k kernel object with spinlock interaction provides heap corruption primitives that can be developed into arbitrary kernel writes and local privilege escalation.\nA:H - Winning the race causes a confirmed slab-use-after-free in dma_buf_fd() (KASAN/lockdep fault), which can panic or oops the kernel even when not fully exploited for code execution."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:37:04.026Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b569f86e2f8dbf6f11d31d3de794d22e18098b23"
        },
        {
          "url": "https://git.kernel.org/stable/c/ead6680f354f83966c796fc7f9463a3171789616"
        }
      ],
      "title": "dma-buf: fix UAF in dma_buf_fd() tracepoint",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63910",
    "datePublished": "2026-07-19T14:55:15.770Z",
    "dateReserved": "2026-07-19T07:54:57.020Z",
    "dateUpdated": "2026-08-05T12:37:04.026Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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