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af_unix: Fix garbage collector racing against connect()

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: af_unix: Fix garbage collector racing against connect() Garbage collector does not take into account the risk of embryo getting enqueued during the garbage collection. If such embryo has a peer that carries SCM_RIGHTS, two consecutive passes of scan_children() may see a different set of children. Leading to an incorrectly elevated inflight count, and then a dangling pointer within the gc_inflight_list. sockets are AF_UNIX/SOCK_STREAM S is an unconnected socket L is a listening in-flight socket bound to addr, not in fdtable V's fd will be passed via sendmsg(), gets inflight count bumped connect(S, addr) sendmsg(S, [V]); close(V) __unix_gc() ---------------- ------------------------- ----------- NS = unix_create1() skb1 = sock_wmalloc(NS) L = unix_find_other(addr) unix_state_lock(L) unix_peer(S) = NS // V count=1 inflight=0 NS = unix_peer(S) skb2 = sock_alloc() skb_queue_tail(NS, skb2[V]) // V became in-flight // V count=2 inflight=1 close(V) // V count=1 inflight=1 // GC candidate condition met for u in gc_inflight_list: if (total_refs == inflight_refs) add u to gc_candidates // gc_candidates={L, V} for u in gc_candidates: scan_children(u, dec_inflight) // embryo (skb1) was not // reachable from L yet, so V's // inflight remains unchanged __skb_queue_tail(L, skb1) unix_state_unlock(L) for u in gc_candidates: if (u.inflight) scan_children(u, inc_inflight_move_tail) // V count=1 inflight=2 (!) If there is a GC-c

Products
Kernel
Affected versions
Not specified
Fixed versions
4.19.314, 5.10.216, 5.15.156, 5.4.275, 6.1.87, 6.6.28, 6.8.7
CVEs
CVE-2024-26923
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 08:42 UTC · Revision 1

Source evidence

af_unix: Fix garbage collector racing against connect()

core-osv · Original source

Published 24 Apr 2024, 21:49 UTC

In the Linux kernel, the following vulnerability has been resolved: af_unix: Fix garbage collector racing against connect() Garbage collector does not take into account the risk of embryo getting enqueued during the garbage collection. If such embryo has a peer that carries SCM_RIGHTS, two consecutive passes of scan_children() may see a different set of children. Leading to an incorrectly elevated inflight count, and then a dangling pointer within the gc_inflight_list. sockets are AF_UNIX/SOCK_STREAM S is an unconnected socket L is a listening in-flight socket bound to addr, not in fdtable V's fd will be passed via sendmsg(), gets inflight count bumped connect(S, addr) sendmsg(S, [V]); close(V) __unix_gc() ---------------- ------------------------- ----------- NS = unix_create1() skb1 = sock_wmalloc(NS) L = unix_find_other(addr) unix_state_lock(L) unix_peer(S) = NS // V count=1 inflight=0 NS = unix_peer(S) skb2 = sock_alloc() skb_queue_tail(NS, skb2[V]) // V became in-flight // V count=2 inflight=1 close(V) // V count=1 inflight=1 // GC candidate condition met for u in gc_inflight_list: if (total_refs == inflight_refs) add u to gc_candidates // gc_candidates={L, V} for u in gc_candidates: scan_children(u, dec_inflight) // embryo (skb1) was not // reachable from L yet, so V's // inflight remains unchanged __skb_queue_tail(L, skb1) unix_state_unlock(L) for u in gc_candidates: if (u.inflight) scan_children(u, inc_inflight_move_tail) // V count=1 inflight=2 (!) If there is a GC-c

osv:CVE-2024-26923

Kernel

Fixed versions: 4.19.314, 5.4.275, 5.10.216, 5.15.156, 6.1.87, 6.6.28, 6.8.7

Complete source record
{
  "id": "bb591d54d6b40f460d3e34a702d1cfc6c65662ef5889872c38c86dcdd69c8743",
  "url": "https://osv.dev/vulnerability/CVE-2024-26923",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "af_unix: Fix garbage collector racing against connect()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: af_unix: Fix garbage collector racing against connect() Garbage collector does not take into account the risk of embryo getting enqueued during the garbage collection. If such embryo has a peer that carries SCM_RIGHTS, two consecutive passes of scan_children() may see a different set of children. Leading to an incorrectly elevated inflight count, and then a dangling pointer within the gc_inflight_list. sockets are AF_UNIX/SOCK_STREAM S is an unconnected socket L is a listening in-flight socket bound to addr, not in fdtable V's fd will be passed via sendmsg(), gets inflight count bumped connect(S, addr) sendmsg(S, [V]); close(V) __unix_gc() ---------------- ------------------------- ----------- NS = unix_create1() skb1 = sock_wmalloc(NS) L = unix_find_other(addr) unix_state_lock(L) unix_peer(S) = NS // V count=1 inflight=0 NS = unix_peer(S) skb2 = sock_alloc() skb_queue_tail(NS, skb2[V]) // V became in-flight // V count=2 inflight=1 close(V) // V count=1 inflight=1 // GC candidate condition met for u in gc_inflight_list: if (total_refs == inflight_refs) add u to gc_candidates // gc_candidates={L, V} for u in gc_candidates: scan_children(u, dec_inflight) // embryo (skb1) was not // reachable from L yet, so V's // inflight remains unchanged __skb_queue_tail(L, skb1) unix_state_unlock(L) for u in gc_candidates: if (u.inflight) scan_children(u, inc_inflight_move_tail) // V count=1 inflight=2 (!) If there is a GC-c",
    "evidence": "osv:CVE-2024-26923",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "4.19.314",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.4.275",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.10.216",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.156",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.87",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.28",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.8.7",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2024-26923",
      "aliases": [
        "A-336268889",
        "ASB-A-336268889",
        "CVE-2024-26923"
      ],
      "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": "1fd05ba5a2f2aa8e7b9b52ef55df850e2e7d54c9"
                },
                {
                  "fixed": "a36ae0ec2353015f0f6762e59f4c2dbc0c906423"
                },
                {
                  "fixed": "343c5372d5e17b306db5f8f3c895539b06e3177f"
                },
                {
                  "fixed": "2e2a03787f4f0abc0072350654ab0ef3324d9db3"
                },
                {
                  "fixed": "e76c2678228f6aec74b305ae30c9374cc2f28a51"
                },
                {
                  "fixed": "b75722be422c276b699200de90527d01c602ea7c"
                },
                {
                  "fixed": "507cc232ffe53a352847893f8177d276c3b532a9"
                },
                {
                  "fixed": "dbdf7bec5c920200077d693193f989cb1513f009"
                },
                {
                  "fixed": "47d8ac011fe1c9251070e1bd64cb10b48193ec51"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-26923.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "2.6.23"
                },
                {
                  "fixed": "4.19.314"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "4.20.0"
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                {
                  "fixed": "5.4.275"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.5.0"
                },
                {
                  "fixed": "5.10.216"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
                },
                {
                  "fixed": "5.15.156"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.87"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.28"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.8.7"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-26923.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:34.415127741Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-265688.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-398330.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-613116.html",
        "https://git.kernel.org/stable/c/2e2a03787f4f0abc0072350654ab0ef3324d9db3",
        "https://git.kernel.org/stable/c/343c5372d5e17b306db5f8f3c895539b06e3177f",
        "https://git.kernel.org/stable/c/47d8ac011fe1c9251070e1bd64cb10b48193ec51",
        "https://git.kernel.org/stable/c/507cc232ffe53a352847893f8177d276c3b532a9",
        "https://git.kernel.org/stable/c/a36ae0ec2353015f0f6762e59f4c2dbc0c906423",
        "https://git.kernel.org/stable/c/b75722be422c276b699200de90527d01c602ea7c",
        "https://git.kernel.org/stable/c/dbdf7bec5c920200077d693193f989cb1513f009",
        "https://git.kernel.org/stable/c/e76c2678228f6aec74b305ae30c9374cc2f28a51",
        "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html",
        "https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/26xxx/CVE-2024-26923.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2024-26923",
        "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/2024/26xxx/CVE-2024-26923.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2024-26923",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 501211,
  "published_at": "2024-04-24T21:49:22.001+00:00"
}