{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2023-52885",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2023-52885"
  ],
  "published": "2024-07-14T07:12:05Z",
  "summary": "SUNRPC: Fix UAF in svc_tcp_listen_data_ready()",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: Fix UAF in svc_tcp_listen_data_ready()\n\nAfter the listener svc_sock is freed, and before invoking svc_tcp_accept()\nfor the established child sock, there is a window that the newsock\nretaining a freed listener svc_sock in sk_user_data which cloning from\nparent. In the race window, if data is received on the newsock, we will\nobserve use-after-free report in svc_tcp_listen_data_ready().\n\nReproduce by two tasks:\n\n1. while :; do rpc.nfsd 0 ; rpc.nfsd; done\n2. while :; do echo \"\" | ncat -4 127.0.0.1 2049 ; done\n\nKASAN report:\n\n  ==================================================================\n  BUG: KASAN: slab-use-after-free in svc_tcp_listen_data_ready+0x1cf/0x1f0 [sunrpc]\n  Read of size 8 at addr ffff888139d96228 by task nc/102553\n  CPU: 7 PID: 102553 Comm: nc Not tainted 6.3.0+ #18\n  Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020\n  Call Trace:\n   <IRQ>\n   dump_stack_lvl+0x33/0x50\n   print_address_description.constprop.0+0x27/0x310\n   print_report+0x3e/0x70\n   kasan_report+0xae/0xe0\n   svc_tcp_listen_data_ready+0x1cf/0x1f0 [sunrpc]\n   tcp_data_queue+0x9f4/0x20e0\n   tcp_rcv_established+0x666/0x1f60\n   tcp_v4_do_rcv+0x51c/0x850\n   tcp_v4_rcv+0x23fc/0x2e80\n   ip_protocol_deliver_rcu+0x62/0x300\n   ip_local_deliver_finish+0x267/0x350\n   ip_local_deliver+0x18b/0x2d0\n   ip_rcv+0x2fb/0x370\n   __netif_receive_skb_one_core+0x166/0x1b0\n   process_backlog+0x24c/0x5e0\n   __napi_poll+0xa2/0x500\n   net_rx_action+0x854/0xc90\n   __do_softirq+0x1bb/0x5de\n   do_softirq+0xcb/0x100\n   </IRQ>\n   <TASK>\n   ...\n   </TASK>\n\n  Allocated by task 102371:\n   kasan_save_stack+0x1e/0x40\n   kasan_set_track+0x21/0x30\n   __kasan_kmalloc+0x7b/0x90\n   svc_setup_socket+0x52/0x4f0 [sunrpc]\n   svc_addsock+0x20d/0x400 [sunrpc]\n   __write_ports_addfd+0x209/0x390 [nfsd]\n   write_ports+0x239/0x2c0 [nfsd]\n   nfsctl_transaction_write+0xac/0x110 [nfsd]\n   vfs_write+0x1c3/0xae0\n   ksys_write+0xed/0x1c0\n   do_syscall_64+0x38/0x90\n   entry_SYSCALL_64_after_hwframe+0x72/0xdc\n\n  Freed by task 102551:\n   kasan_save_stack+0x1e/0x40\n   kasan_set_track+0x21/0x30\n   kasan_save_free_info+0x2a/0x50\n   __kasan_slab_free+0x106/0x190\n   __kmem_cache_free+0x133/0x270\n   svc_xprt_free+0x1e2/0x350 [sunrpc]\n   svc_xprt_destroy_all+0x25a/0x440 [sunrpc]\n   nfsd_put+0x125/0x240 [nfsd]\n   nfsd_svc+0x2cb/0x3c0 [nfsd]\n   write_threads+0x1ac/0x2a0 [nfsd]\n   nfsctl_transaction_write+0xac/0x110 [nfsd]\n   vfs_write+0x1c3/0xae0\n   ksys_write+0xed/0x1c0\n   do_syscall_64+0x38/0x90\n   entry_SYSCALL_64_after_hwframe+0x72/0xdc\n\nFix the UAF by simply doing nothing in svc_tcp_listen_data_ready()\nif state != TCP_LISTEN, that will avoid dereferencing svsk for all\nchild socket.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.21-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v6",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v7",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v8",
            "binary_version": "1:6.1.21-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.21-1+rpt1": {
            "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed",
            "upstream_version": "6.1.21",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.39"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2023-52885"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c7b8c2d06e437639694abe76978e915cfb73f428"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/dfc896c4a75cb8cd7cb2dfd9b469cf1e3f004254"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/42725e5c1b181b757ba11d804443922982334d9b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/cd5ec3ee52ce4b7e283cc11facfa420c297c8065"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/fbf4ace39b2e4f3833236afbb2336edbafd75eee"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ef047411887ff0845afd642d6a687819308e1a4e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7e1f989055622fd086c5dfb291fc72adf5660b6f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/fc80fc2d4e39137869da3150ee169b40bf879287"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:24:39Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 8.1,
      "cvss_v3_severity": "High",
      "scenario": "AV:N - The UAF is triggered from softirq TCP receive (tcp_data_queue \u2192 svc_tcp_listen_data_ready) on an nfsd/SUNRPC listening service; a remote peer only needs to complete a TCP handshake to port 2049 and send data, matching kernel guidance that nfsd is Network.\nAC:H - The UAF window requires the listener svc_sock to be freed (nfsd/lockd/callback teardown via svc_xprt_destroy_all) while a child still holds the inherited sk_user_data pointer\u2014a victim-side restart/shutdown the remote attacker cannot cause, only race against.\nPR:N - The vulnerable callback runs on a pre-accept child socket during TCP data delivery, before nfsd accepts the connection or performs any RPC authentication, so an unauthenticated network peer suffices.\nUI:N - Exploitation is driven by attacker-sent TCP segments to an already-running SUNRPC listener in softirq context; no victim mount, file open, or other interactive action is required at exploit time.\nS:U - The use-after-free corrupts host kernel heap (svc_sock) within the same OS security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - This is a slab use-after-free of struct svc_sock; reclaim of the freed object lets the callback path read attacker-controlled fields (including sk_odata), enabling arbitrary kernel disclosure per UAF guidance.\nI:H - svc_tcp_listen_data_ready invokes svsk->sk_odata(sk) from the freed object, so a reclaimed function pointer yields a direct control-flow hijack/write primitive characteristic of exploitable kernel UAFs.\nA:H - The KASAN report documents a reproducible slab-use-after-free oops in svc_tcp_listen_data_ready from net_rx softirq, so availability impact is a full kernel crash."
    }
  }
}