net/smc: fix warning in smc_rx_splice() when calling get_page()

{
  "id": "07f2c31c9576c6e7df71e25d5fe0727f0474bc3211dd1e82bcb1241c98d4750d",
  "url": "https://osv.dev/vulnerability/CVE-2025-40012",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net/smc: fix warning in smc_rx_splice() when calling get_page()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net/smc: fix warning in smc_rx_splice() when calling get_page() smc_lo_register_dmb() allocates DMB buffers with kzalloc(), which are later passed to get_page() in smc_rx_splice(). Since kmalloc memory is not page-backed, this triggers WARN_ON_ONCE() in get_page() and prevents holding a refcount on the buffer. This can lead to use-after-free if the memory is released before splice_to_pipe() completes. Use folio_alloc() instead, ensuring DMBs are page-backed and safe for get_page(). WARNING: CPU: 18 PID: 12152 at ./include/linux/mm.h:1330 smc_rx_splice+0xaf8/0xe20 [smc] CPU: 18 UID: 0 PID: 12152 Comm: smcapp Kdump: loaded Not tainted 6.17.0-rc3-11705-g9cf4672ecfee #10 NONE Hardware name: IBM 3931 A01 704 (z/VM 7.4.0) Krnl PSW : 0704e00180000000 000793161032696c (smc_rx_splice+0xafc/0xe20 [smc]) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3 Krnl GPRS: 0000000000000000 001cee80007d3001 00077400000000f8 0000000000000005 0000000000000001 001cee80007d3006 0007740000001000 001c000000000000 000000009b0c99e0 0000000000001000 001c0000000000f8 001c000000000000 000003ffcc6f7c88 0007740003e98000 0007931600000005 000792969b2ff7b8 Krnl Code: 0007931610326960: af000000 mc 0,0 0007931610326964: a7f4ff43 brc 15,00079316103267ea #0007931610326968: af000000 mc 0,0 >000793161032696c: a7f4ff3f brc 15,00079316103267ea 0007931610326970: e320f1000004 lg %r2,256(%r15) 0007931610326976: c0e53fd1b5f5 brasl %r14,000793168f",
    "evidence": "osv:CVE-2025-40012",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.50",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.16.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2025-40012",
      "aliases": [
        "CVE-2025-40012"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "f7a22071dbf316c982fb44308874bd7ad9ac2091"
                },
                {
                  "fixed": "14fc4fdae42e34d7ee871b292ac2ecc61c2c5de7"
                },
                {
                  "fixed": "d5411685dc2f6ac7bdf01a0a204d56cae38c6cf6"
                },
                {
                  "fixed": "a35c04de2565db191726b5741e6b66a35002c652"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40012.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.10.0"
                },
                {
                  "fixed": "6.12.50"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.16.10"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40012.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:48.851280622Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/14fc4fdae42e34d7ee871b292ac2ecc61c2c5de7",
        "https://git.kernel.org/stable/c/a35c04de2565db191726b5741e6b66a35002c652",
        "https://git.kernel.org/stable/c/d5411685dc2f6ac7bdf01a0a204d56cae38c6cf6",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40012.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-40012",
        "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/2025/40xxx/CVE-2025-40012.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-40012",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517167,
  "published_at": "2025-10-20T15:26:57.214+00:00"
}