{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-74609",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2026-74609"
  ],
  "published": "2026-08-22T15:32:12Z",
  "summary": "tipc: read le->link under the node lock in tipc_node_link_down()",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: read le->link under the node lock in tipc_node_link_down()\n\ntipc_node_link_down() caches the link pointer before taking n->lock:\n\n\tstruct tipc_link *l = le->link;\t\t/* unlocked */\n\n\tif (!l)\n\t\treturn;\n\ttipc_node_write_lock(n);\n\tif (!tipc_link_is_establishing(l)) {\t/* deref l */\n\t...\n\t\ttipc_link_reset(l);\t\t/* write into l */\n\tif (delete) {\n\t\tkfree(l);\n\t\tle->link = NULL;\n\nThe delete=true caller frees that very object under n->lock, so the lock\ndoes not protect the cached pointer against it:\n\n - CPU A, delete=false: tipc_rcv() on TIPC_LINK_DOWN_EVT, or the link\n   supervision timer via tipc_node_timeout(), reads l unlocked and then\n   dereferences it under n->lock;\n - CPU B, delete=true: netlink TIPC_NL_BEARER_DISABLE -> bearer_disable()\n   -> tipc_node_delete_links() -> tipc_node_link_down(n, bearer_id, true)\n   -> kfree(l).\n\nThe link is freed with plain kfree(), not kfree_rcu(), and for UDP bearers\ndisable_media() only schedules the asynchronous cleanup_bearer() work, so\nits synchronize_net() runs after the links are already gone.  An in-flight\nCPU A that has read l therefore dereferences freed memory once B frees it:\na use-after-free read in tipc_link_is_establishing(), and a use-after-free\nwrite via tipc_link_reset() on the establishing branch.\n\nThe following trace was captured on 7.2.0-rc5-00284-gaf39eb111ce6:\n\n  BUG: KASAN: slab-use-after-free in tipc_link_is_establishing (net/tipc/link.c:285)\n  Read of size 4 at addr ffff88802e2aa068 by task swapper/2/0\n   tipc_link_is_establishing (net/tipc/link.c:285)\n   tipc_node_link_down (net/tipc/node.c:1076)\n   tipc_node_timeout (net/tipc/node.c:843)\n  Allocated by task 9549:\n   tipc_link_create (net/tipc/link.c:490)\n   tipc_node_check_dest (net/tipc/node.c:1279)\n   tipc_disc_rcv (net/tipc/discover.c:252)\n   tipc_udp_recv (net/tipc/udp_media.c:389)\n  Freed by task 9549:\n   tipc_node_link_down (net/tipc/node.c:1084)\n   tipc_node_delete_links (net/tipc/node.c:1320)\n   bearer_disable (net/tipc/bearer.c:414)\n   __tipc_nl_bearer_disable (net/tipc/bearer.c:992)\n\nMove the le->link read inside tipc_node_write_lock(), so it is serialised\nagainst the kfree() in the delete path.  A racing teardown now either has\nnot run yet, and we see a valid link, or has already run, and we see NULL.",
  "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-2026-74609"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2be741ad565c610871a6a95062c12c39da7168fd"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/69d209461c110388710e483a130caf051e4fd09a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/de017c22135f545ca4e65d1eada22887b64958eb"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/47ba70891b10b2feb52462086b7fcd2ad75d3ce3"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a714d62513befef37f71f4ae89bb1fe173b65f2e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c3f2347a47754eac690967cfd82cb6d559817b07"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/5558a8312452ddb21eff22b1cbd84302ad951944"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/cba9ccb47e9fa4cc77692fb896cc5ab57a667882"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-25T05:42:41Z"
  }
}