{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-40983",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2024-40983"
  ],
  "published": "2024-07-12T12:34:08Z",
  "summary": "tipc: force a dst refcount before doing decryption",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: force a dst refcount before doing decryption\n\nAs it says in commit 3bc07321ccc2 (\"xfrm: Force a dst refcount before\nentering the xfrm type handlers\"):\n\n\"Crypto requests might return asynchronous. In this case we leave the\n rcu protected region, so force a refcount on the skb's destination\n entry before we enter the xfrm type input/output handlers.\"\n\nOn TIPC decryption path it has the same problem, and skb_dst_force()\nshould be called before doing decryption to avoid a possible crash.\n\nShuang reported this issue when this warning is triggered:\n\n  [] WARNING: include/net/dst.h:337 tipc_sk_rcv+0x1055/0x1ea0 [tipc]\n  [] Kdump: loaded Tainted: G W --------- - - 4.18.0-496.el8.x86_64+debug\n  [] Workqueue: crypto cryptd_queue_worker\n  [] RIP: 0010:tipc_sk_rcv+0x1055/0x1ea0 [tipc]\n  [] Call Trace:\n  [] tipc_sk_mcast_rcv+0x548/0xea0 [tipc]\n  [] tipc_rcv+0xcf5/0x1060 [tipc]\n  [] tipc_aead_decrypt_done+0x215/0x2e0 [tipc]\n  [] cryptd_aead_crypt+0xdb/0x190\n  [] cryptd_queue_worker+0xed/0x190\n  [] process_one_work+0x93d/0x17e0",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/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": "6.1.96",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-40983"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3eb1b39627892c4e26cb0162b75725aa5fcc60c8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/692803b39a36e63ac73208e0a3769ae6a2f9bc76"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/623c90d86a61e3780f682b32928af469c66ec4c2"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b57a4a2dc8746cea58a922ebe31b6aa629d69d93"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6808b41371670c51feea14f63ade211e78100930"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2ebe8f840c7450ecbfca9d18ac92e9ce9155e269"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:52:36Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 9.8,
      "cvss_v3_severity": "Critical",
      "scenario": "AV:N - The bug only manifests on the TIPC UDP bearer path (`tipc_udp_recv()` \u2192 `tipc_rcv()`, default UDP port 6118), where the skb still carries the noref input-route dst set by `ip_route_input_noref()`; L2 bearers carry no dst at all, so the affected configuration is precisely the routable, remotely reachable one, reachable from any host that can send UDP to the node.\nAC:L - Once TIPC crypto is keyed, every asynchronously completed decryption reaches `__sk_add_backlog()`/`__sock_queue_rcv_skb()` \u2192 `skb_dst_force()` from a `cryptd_queue_worker` context outside RCU, tripping `WARN_ON(!rcu_read_lock_held())` deterministically, and the attacker can force the async path at will since `aead_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, ...)` makes a packet flood push requests into the crypto backlog (-EBUSY/-EINPROGRESS), while hardware AEAD offload (QAT/CAAM/CCP) makes it async unconditionally. `CONFIG_TIPC_CRYPTO` is `default y`, so no rare build option is involved, and the attacker can also churn the input-route cache with spoofed sources to widen the window in which the noref dst is actually RCU-freed.\nPR:N - The attacker needs no account, capability, or any privilege on the target host \u2014 the path is entered purely by sending TIPC packets to the bearer socket; in TIPC cluster/master-key mode the AEAD key is a single network-wide shared secret held identically by every node, so any peer or compromised cluster member (and an on-path injector replaying an in-flight encrypted frame) reaches the vulnerable code with zero authorization from the vulnerable component.\nUI:N - Delivery of network packets to a configured TIPC bearer is processed entirely by the kernel with no action by any local user or administrator.\nS:U - The stale dst reference, the WARN and any resulting corruption are confined to kernel memory within the same security authority; no VM, IOMMU, container or sandbox boundary is crossed.\nC:H - After the crypto callback leaves the RCU read-side section, `skb_dst_force()` calls `dst_hold_safe()` on a `struct rtable` that may already have been released by `dst_destroy_rcu()`, reading freed slab memory; worse, the skb then loses `SKB_DST_NOREF` and holds what the stack treats as a refcounted pointer into reallocated memory, whose later dereference (`dst->ops`, `dst->dev`) can expose contents of an attacker-groomed object \u2014 a use-after-free of this class is treated as High.\nI:H - `dst_hold_safe()` performs a read-modify-write (`rcuref_get`/`atomic_inc_not_zero`) on freed memory, and the subsequent `dst_release()` decrements the same location, giving an attacker who sprays the freed `rtable` slab an increment/decrement primitive plus a premature-free trigger on an unrelated object, including control over the `dst->ops` function-pointer table used on release.\nA:H - The missing refcount reliably trips `WARN_ON(!rcu_read_lock_held())` in `skb_dst_force()` (fatal on the common `panic_on_warn=1` hardened/cloud deployments), and the commit itself states the intent is \"to avoid a possible crash\" \u2014 a use-after-free of the dst entry oopses the kernel, and the condition is repeatable on demand by continued packet transmission."
    }
  }
}