{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-55916",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2024-55916"
  ],
  "published": "2025-01-11T12:37:33Z",
  "summary": "Drivers: hv: util: Avoid accessing a ringbuffer not initialized yet",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nDrivers: hv: util: Avoid accessing a ringbuffer not initialized yet\n\nIf the KVP (or VSS) daemon starts before the VMBus channel's ringbuffer is\nfully initialized, we can hit the panic below:\n\nhv_utils: Registering HyperV Utility Driver\nhv_vmbus: registering driver hv_utils\n...\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nCPU: 44 UID: 0 PID: 2552 Comm: hv_kvp_daemon Tainted: G E 6.11.0-rc3+ #1\nRIP: 0010:hv_pkt_iter_first+0x12/0xd0\nCall Trace:\n...\n vmbus_recvpacket\n hv_kvp_onchannelcallback\n vmbus_on_event\n tasklet_action_common\n tasklet_action\n handle_softirqs\n irq_exit_rcu\n sysvec_hyperv_stimer0\n </IRQ>\n <TASK>\n asm_sysvec_hyperv_stimer0\n...\n kvp_register_done\n hvt_op_read\n vfs_read\n ksys_read\n __x64_sys_read\n\nThis can happen because the KVP/VSS channel callback can be invoked\neven before the channel is fully opened:\n1) as soon as hv_kvp_init() -> hvutil_transport_init() creates\n/dev/vmbus/hv_kvp, the kvp daemon can open the device file immediately and\nregister itself to the driver by writing a message KVP_OP_REGISTER1 to the\nfile (which is handled by kvp_on_msg() ->kvp_handle_handshake()) and\nreading the file for the driver's response, which is handled by\nhvt_op_read(), which calls hvt->on_read(), i.e. kvp_register_done().\n\n2) the problem with kvp_register_done() is that it can cause the\nchannel callback to be called even before the channel is fully opened,\nand when the channel callback is starting to run, util_probe()->\nvmbus_open() may have not initialized the ringbuffer yet, so the\ncallback can hit the panic of NULL pointer dereference.\n\nTo reproduce the panic consistently, we can add a \"ssleep(10)\" for KVP in\n__vmbus_open(), just before the first hv_ringbuffer_init(), and then we\nunload and reload the driver hv_utils, and run the daemon manually within\nthe 10 seconds.\n\nFix the panic by reordering the steps in util_probe() so the char dev\nentry used by the KVP or VSS daemon is not created until after\nvmbus_open() has completed. This reordering prevents the race condition\nfrom happening.",
  "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": "6.1.122",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-55916"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f091a224a2c82f1e302b1768d73bb6332f687321"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d81f4e73aff9b861671df60e5100ad25cc16fbf8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/042253c57be901bfd19f15b68267442b70f510d5"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/718fe694a334be9d1a89eed22602369ac18d6583"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/89fcec5e466b3ac9b376e0d621c71effa1a7983f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3dd7a30c6d7f90afcf19e9b072f572ba524d7ec6"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/07a756a49f4b4290b49ea46e089cbe6f79ff8d26"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-05-12T04:54:46Z"
  }
}