{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2023-53343",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2023-53343"
  ],
  "published": "2025-09-17T14:57:20Z",
  "summary": "icmp6: Fix null-ptr-deref of ip6_null_entry->rt6i_idev in icmp6_dev().",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nicmp6: Fix null-ptr-deref of ip6_null_entry->rt6i_idev in icmp6_dev().\n\nWith some IPv6 Ext Hdr (RPL, SRv6, etc.), we can send a packet that\nhas the link-local address as src and dst IP and will be forwarded to\nan external IP in the IPv6 Ext Hdr.\n\nFor example, the script below generates a packet whose src IP is the\nlink-local address and dst is updated to 11::.\n\n  # for f in $(find /proc/sys/net/ -name *seg6_enabled*); do echo 1 > $f; done\n  # python3\n  >>> from socket import *\n  >>> from scapy.all import *\n  >>>\n  >>> SRC_ADDR = DST_ADDR = \"fe80::5054:ff:fe12:3456\"\n  >>>\n  >>> pkt = IPv6(src=SRC_ADDR, dst=DST_ADDR)\n  >>> pkt /= IPv6ExtHdrSegmentRouting(type=4, addresses=[\"11::\", \"22::\"], segleft=1)\n  >>>\n  >>> sk = socket(AF_INET6, SOCK_RAW, IPPROTO_RAW)\n  >>> sk.sendto(bytes(pkt), (DST_ADDR, 0))\n\nFor such a packet, we call ip6_route_input() to look up a route for the\nnext destination in these three functions depending on the header type.\n\n  * ipv6_rthdr_rcv()\n  * ipv6_rpl_srh_rcv()\n  * ipv6_srh_rcv()\n\nIf no route is found, ip6_null_entry is set to skb, and the following\ndst_input(skb) calls ip6_pkt_drop().\n\nFinally, in icmp6_dev(), we dereference skb_rt6_info(skb)->rt6i_idev->dev\nas the input device is the loopback interface.  Then, we have to check if\nskb_rt6_info(skb)->rt6i_idev is NULL or not to avoid NULL pointer deref\nfor ip6_null_entry.\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\n PF: supervisor read access in kernel mode\n PF: error_code(0x0000) - not-present page\nPGD 0 P4D 0\nOops: 0000 [#1] PREEMPT SMP PTI\nCPU: 0 PID: 157 Comm: python3 Not tainted 6.4.0-11996-gb121d614371c #35\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014\nRIP: 0010:icmp6_send (net/ipv6/icmp.c:436 net/ipv6/icmp.c:503)\nCode: fe ff ff 48 c7 40 30 c0 86 5d 83 e8 c6 44 1c 00 e9 c8 fc ff ff 49 8b 46 58 48 83 e0 fe 0f 84 4a fb ff ff 48 8b 80 d0 00 00 00 <48> 8b 00 44 8b 88 e0 00 00 00 e9 34 fb ff ff 4d 85 ed 0f 85 69 01\nRSP: 0018:ffffc90000003c70 EFLAGS: 00000286\nRAX: 0000000000000000 RBX: 0000000000000001 RCX: 00000000000000e0\nRDX: 0000000000000021 RSI: 0000000000000000 RDI: ffff888006d72a18\nRBP: ffffc90000003d80 R08: 0000000000000000 R09: 0000000000000001\nR10: ffffc90000003d98 R11: 0000000000000040 R12: ffff888006d72a10\nR13: 0000000000000000 R14: ffff8880057fb800 R15: ffffffff835d86c0\nFS:  00007f9dc72ee740(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000000000000000 CR3: 00000000057b2000 CR4: 00000000007506f0\nPKRU: 55555554\nCall Trace:\n <IRQ>\n ip6_pkt_drop (net/ipv6/route.c:4513)\n ipv6_rthdr_rcv (net/ipv6/exthdrs.c:640 net/ipv6/exthdrs.c:686)\n ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:437 (discriminator 5))\n ip6_input_finish (./include/linux/rcupdate.h:781 net/ipv6/ip6_input.c:483)\n __netif_receive_skb_one_core (net/core/dev.c:5455)\n process_backlog (./include/linux/rcupdate.h:781 net/core/dev.c:5895)\n __napi_poll (net/core/dev.c:6460)\n net_rx_action (net/core/dev.c:6529 net/core/dev.c:6660)\n __do_softirq (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/irq.h:142 kernel/softirq.c:554)\n do_softirq (kernel/softirq.c:454 kernel/softirq.c:441)\n </IRQ>\n <TASK>\n __local_bh_enable_ip (kernel/softirq.c:381)\n __dev_queue_xmit (net/core/dev.c:4231)\n ip6_finish_output2 (./include/net/neighbour.h:544 net/ipv6/ip6_output.c:135)\n rawv6_sendmsg (./include/net/dst.h:458 ./include/linux/netfilter.h:303 net/ipv6/raw.c:656 net/ipv6/raw.c:914)\n sock_sendmsg (net/socket.c:725 net/socket.c:748)\n __sys_sendto (net/socket.c:2134)\n __x64_sys_sendto (net/socket.c:2146 net/socket.c:2142 net/socket.c:2142)\n do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)\n entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)\nRIP: 0033:0x7f9dc751baea\nCode: d8 64 89 02 48 c7 c0 ff f\n---truncated---",
  "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": "6.1.40"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2023-53343"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8803c59fde4dd370a627dfbf7183682fa0cabf70"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/61b4c4659746959056450b92a5d7e6bc1243b31b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d30ddd7ff15df9d91a793ce3f06f0190ff7afacc"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3fabca5d9cae0140b6aad09a1c6b9aa57089fbb8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1462e9d9aa52d14665eaca6d89d22c4af44ede04"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/aa657d319e6c7502a4eb85cc0ee80cc81b8e5724"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2aaa8a15de73874847d62eb595c6683bface80fd"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-05-12T04:54:46Z"
  }
}