{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-74631",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-74631"
  ],
  "published": "2026-08-22T15:32:12Z",
  "summary": "net: smc: fix splice entry lifetime imbalance in smc_rx_splice",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: smc: fix splice entry lifetime imbalance in smc_rx_splice\n\nsmc_rx_splice() passes pages to splice_to_pipe() before taking the\nreferences that cover the lifetime of each splice entry. In the\nVM-backed RMB path, splice_to_pipe() may drop unqueued entries through\nsmc_rx_spd_release(), while queued entries are released later via the\npipe buffer callback.\n\nThe old post-splice accounting also derives the number of queued VM pages\nfrom an offset mutated while building the descriptor, and a multi-page\nsplice pairs one sock_hold() with multiple sock_put() calls.\n\nTake the page and socket references for every candidate entry before\nsplice_to_pipe(), and drop the matching private state, page reference,\nand socket reference from smc_rx_spd_release() for entries that never\nget queued. This fixes a refcount imbalance that can underflow page\nrefcounts and trigger a use-after-free.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.183",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-74631"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7ddc7af2ae7fc5a0c0635b245c0824c8b76de5cb"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/07ad246529d136d5ef441d5ab4c305d132ff3090"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c841789e456ec6751342fa800639ce8e82ff0e6b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/af02c67ce654356c58db20a0bb2db33ace3b07a8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ca8342b5fc24c249fdb998468f6a168b457c67e5"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0b7d54cedea5cb158e21925ae0c6c2f5c87ed2a0"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/4515c78f4d9fd577270f012efeb062ea58b3682d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/5d9686af2976741bbd79b150d1c9e60b81e7f12e"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-25T05:42:41Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 8.4,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - smc_rx_splice is only reached via splice()/tee() on an SMC socket FD (syscall -> smc_splice_read -> smc_rx_recvmsg with pipe set); remote SMC peers can supply receive-buffer data but cannot execute the vulnerable splice path without a local process invoking splice on that socket.\nAC:L - The attacker controls splice length, can nearly fill the destination pipe to force splice_to_pipe to drop unqueued entries via smc_rx_spd_release, and can hit the multi-page VM-backed RMB path (smcr_buf_type or mixed-buffer vmalloc fallback); no timing race or external victim state is required.\nPR:N - Exploitation requires only completing an SMC session as a network peer to a victim that reads with splice (common zero-copy SMC pattern); no local account, capabilities, or namespace-admin rights on the victim host are needed beyond normal remote connectivity to the SMC service.\nUI:N - No per-exploit victim action is needed beyond an application already using splice on SMC receive; a malicious peer can deliver the receive data while the victim's normal automated splice path triggers the refcount imbalance without prompts or manual steps.\nS:U - Impact is kernel page refcount underflow and use-after-free within the same kernel security boundary, enabling privilege escalation or crash on the host; it does not cross VM, IOMMU, or sandbox authority boundaries.\nC:H - Refcount imbalance lets smc_rx_spd_release and pipe-buffer teardown free pages while still referenced, creating a UAF on RMB pages that can be turned into arbitrary kernel memory disclosure via heap reuse and spraying.\nI:H - Corrupted page lifetime and dangling pipe_buffer state enable heap metadata corruption and arbitrary kernel writes from the UAF primitive, supporting control-flow hijacking and local privilege escalation.\nA:H - Page refcount underflow and UAF during splice teardown can cause immediate kernel oops/panic; repeated splice from an SMC peer reliably triggers denial-of-service even when full exploitation is not attempted."
    }
  }
}