net/tcp: Fix socket memory leak in TCP-AO failure handling for IPv6

{
  "id": "6019a1f86a72dd54b124f861d682c16844eefac769c93b9bbdcbe84e259bcdaa",
  "url": "https://osv.dev/vulnerability/CVE-2025-39852",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net/tcp: Fix socket memory leak in TCP-AO failure handling for IPv6",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net/tcp: Fix socket memory leak in TCP-AO failure handling for IPv6 When tcp_ao_copy_all_matching() fails in tcp_v6_syn_recv_sock() it just exits the function. This ends up causing a memory-leak: unreferenced object 0xffff0000281a8200 (size 2496): comm \"softirq\", pid 0, jiffies 4295174684 hex dump (first 32 bytes): 7f 00 00 06 7f 00 00 06 00 00 00 00 cb a8 88 13 ................ 0a 00 03 61 00 00 00 00 00 00 00 00 00 00 00 00 ...a............ backtrace (crc 5ebdbe15): kmemleak_alloc+0x44/0xe0 kmem_cache_alloc_noprof+0x248/0x470 sk_prot_alloc+0x48/0x120 sk_clone_lock+0x38/0x3b0 inet_csk_clone_lock+0x34/0x150 tcp_create_openreq_child+0x3c/0x4a8 tcp_v6_syn_recv_sock+0x1c0/0x620 tcp_check_req+0x588/0x790 tcp_v6_rcv+0x5d0/0xc18 ip6_protocol_deliver_rcu+0x2d8/0x4c0 ip6_input_finish+0x74/0x148 ip6_input+0x50/0x118 ip6_sublist_rcv+0x2fc/0x3b0 ipv6_list_rcv+0x114/0x170 __netif_receive_skb_list_core+0x16c/0x200 netif_receive_skb_list_internal+0x1f0/0x2d0 This is because in tcp_v6_syn_recv_sock (and the IPv4 counterpart), when exiting upon error, inet_csk_prepare_forced_close() and tcp_done() need to be called. They make sure the newsk will end up being correctly free'd. tcp_v4_syn_recv_sock() makes this very clear by having the put_and_exit label that takes care of things. So, this patch here makes sure tcp_v4_syn_recv_sock and tcp_v6_syn_recv_sock have similar error-handling and thus fixes the leak for TCP-AO.",
    "evidence": "osv:CVE-2025-39852",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
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        "prerequisites": [],
        "fixed_versions": [
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            "value": "6.12.46",
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    "severity": "medium",
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      "id": "CVE-2025-39852",
      "aliases": [
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      "modified": "2026-10-28T02:30:50.923500600Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/3d2b356d994a8801acb397cafd28b13672c37ab5",
        "https://git.kernel.org/stable/c/46d33c878fc0b3d7570366b2c9912395b3f4e701",
        "https://git.kernel.org/stable/c/fa390321aba0a54d0f7ae95ee4ecde1358bb9234",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39852.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-39852",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
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      "provider_metadata": {
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
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  "source_id": "core-osv",
  "document_id": 519536,
  "published_at": "2025-09-19T15:26:24.312+00:00"
}