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OESA-2025-2006 (CVE-2025-21920)

Vulnerability from osv_openeuler – Published: 2025-08-15 11:09 – Updated: 2026-08-06 11:09 – Source website
VLAI
Summary
kernel security update
Details

The Linux Kernel, the operating system core itself.

Security Fix(es):

In the Linux kernel, the following vulnerability has been resolved:

vlan: enforce underlying device type

Currently, VLAN devices can be created on top of non-ethernet devices.

Besides the fact that it doesn't make much sense, this also causes a bug which leaks the address of a kernel function to usermode.

When creating a VLAN device, we initialize GARP (garp_init_applicant) and MRP (mrp_init_applicant) for the underlying device.

As part of the initialization process, we add the multicast address of each applicant to the underlying device, by calling dev_mc_add.

__dev_mc_add uses dev->addr_len to determine the length of the new multicast address.

This causes an out-of-bounds read if dev->addr_len is greater than 6, since the multicast addresses provided by GARP and MRP are only 6 bytes long.

This behaviour can be reproduced using the following commands:

ip tunnel add gretest mode ip6gre local ::1 remote ::2 dev lo ip l set up dev gretest ip link add link gretest name vlantest type vlan id 100

Then, the following command will display the address of garp_pdu_rcv:

ip maddr show | grep 01:80:c2:00:00:21

Fix the bug by enforcing the type of the underlying device during VLAN device initialization.(CVE-2025-21920)

In the Linux kernel, the following vulnerability has been resolved:

net: gso: fix ownership in __udp_gso_segment

In __udp_gso_segment the skb destructor is removed before segmenting the skb but the socket reference is kept as-is. This is an issue if the original skb is later orphaned as we can hit the following bug:

kernel BUG at ./include/linux/skbuff.h:3312! (skb_orphan) RIP: 0010:ip_rcv_core+0x8b2/0xca0 Call Trace: ip_rcv+0xab/0x6e0 __netif_receive_skb_one_core+0x168/0x1b0 process_backlog+0x384/0x1100 __napi_poll.constprop.0+0xa1/0x370 net_rx_action+0x925/0xe50

The above can happen following a sequence of events when using OpenVSwitch, when an OVS_ACTION_ATTR_USERSPACE action precedes an OVS_ACTION_ATTR_OUTPUT action:

  1. OVS_ACTION_ATTR_USERSPACE is handled (in do_execute_actions): the skb goes through queue_gso_packets and then __udp_gso_segment, where its destructor is removed.
  2. The segments' data are copied and sent to userspace.
  3. OVS_ACTION_ATTR_OUTPUT is handled (in do_execute_actions) and the same original skb is sent to its path.
  4. If it later hits skb_orphan, we hit the bug.

Fix this by also removing the reference to the socket in __udp_gso_segment.(CVE-2025-21926)

In the Linux kernel, the following vulnerability has been resolved:

net: atm: fix use after free in lec_send()

The ->send() operation frees skb so save the length before calling ->send() to avoid a use after free.(CVE-2025-22004)

In the Linux kernel, the following vulnerability has been resolved:

posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()

If an exiting non-autoreaping task has already passed exit_notify() and calls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent or debugger right after unlock_task_sighand().

If a concurrent posix_cpu_timer_del() runs at that moment, it won't be able to detect timer->it.cpu.firing != 0: cpu_timer_task_rcu() and/or lock_task_sighand() will fail.

Add the tsk->exit_state check into run_posix_cpu_timers() to fix this.

This fix is not needed if CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, because exit_task_work() is called before exit_notify(). But the check still makes sense, task_work_add(&tsk->posix_cputimers_work.work) will fail anyway in this case.(CVE-2025-38352)

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "aarch64": [
          "bpftool-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "bpftool-debuginfo-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "kernel-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "kernel-debuginfo-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "kernel-debugsource-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "kernel-devel-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "kernel-headers-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "kernel-source-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "kernel-tools-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "kernel-tools-debuginfo-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "kernel-tools-devel-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "perf-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "perf-debuginfo-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "python3-perf-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm",
          "python3-perf-debuginfo-5.10.0-277.0.0.180.oe2203sp4.aarch64.rpm"
        ],
        "src": [
          "kernel-5.10.0-277.0.0.180.oe2203sp4.src.rpm"
        ],
        "x86_64": [
          "bpftool-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "bpftool-debuginfo-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "kernel-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "kernel-debuginfo-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "kernel-debugsource-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "kernel-devel-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "kernel-headers-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "kernel-source-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "kernel-tools-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "kernel-tools-debuginfo-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "kernel-tools-devel-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "perf-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "perf-debuginfo-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "python3-perf-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm",
          "python3-perf-debuginfo-5.10.0-277.0.0.180.oe2203sp4.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:22.03-LTS-SP4",
        "name": "kernel",
        "purl": "pkg:rpm/openEuler/kernel\u0026distro=openEuler-22.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "5.10.0-277.0.0.180.oe2203sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "High"
  },
  "details": "The Linux Kernel, the operating system core itself.\r\n\r\nSecurity Fix(es):\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nvlan: enforce underlying device type\n\nCurrently, VLAN devices can be created on top of non-ethernet devices.\n\nBesides the fact that it doesn\u0026apos;t make much sense, this also causes a\nbug which leaks the address of a kernel function to usermode.\n\nWhen creating a VLAN device, we initialize GARP (garp_init_applicant)\nand MRP (mrp_init_applicant) for the underlying device.\n\nAs part of the initialization process, we add the multicast address of\neach applicant to the underlying device, by calling dev_mc_add.\n\n__dev_mc_add uses dev-\u0026gt;addr_len to determine the length of the new\nmulticast address.\n\nThis causes an out-of-bounds read if dev-\u0026gt;addr_len is greater than 6,\nsince the multicast addresses provided by GARP and MRP are only 6\nbytes long.\n\nThis behaviour can be reproduced using the following commands:\n\nip tunnel add gretest mode ip6gre local ::1 remote ::2 dev lo\nip l set up dev gretest\nip link add link gretest name vlantest type vlan id 100\n\nThen, the following command will display the address of garp_pdu_rcv:\n\nip maddr show | grep 01:80:c2:00:00:21\n\nFix the bug by enforcing the type of the underlying device during VLAN\ndevice initialization.(CVE-2025-21920)\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: gso: fix ownership in __udp_gso_segment\n\nIn __udp_gso_segment the skb destructor is removed before segmenting the\nskb but the socket reference is kept as-is. This is an issue if the\noriginal skb is later orphaned as we can hit the following bug:\n\n  kernel BUG at ./include/linux/skbuff.h:3312!  (skb_orphan)\n  RIP: 0010:ip_rcv_core+0x8b2/0xca0\n  Call Trace:\n   ip_rcv+0xab/0x6e0\n   __netif_receive_skb_one_core+0x168/0x1b0\n   process_backlog+0x384/0x1100\n   __napi_poll.constprop.0+0xa1/0x370\n   net_rx_action+0x925/0xe50\n\nThe above can happen following a sequence of events when using\nOpenVSwitch, when an OVS_ACTION_ATTR_USERSPACE action precedes an\nOVS_ACTION_ATTR_OUTPUT action:\n\n1. OVS_ACTION_ATTR_USERSPACE is handled (in do_execute_actions): the skb\n   goes through queue_gso_packets and then __udp_gso_segment, where its\n   destructor is removed.\n2. The segments\u0026apos; data are copied and sent to userspace.\n3. OVS_ACTION_ATTR_OUTPUT is handled (in do_execute_actions) and the\n   same original skb is sent to its path.\n4. If it later hits skb_orphan, we hit the bug.\n\nFix this by also removing the reference to the socket in\n__udp_gso_segment.(CVE-2025-21926)\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: atm: fix use after free in lec_send()\n\nThe -\u0026gt;send() operation frees skb so save the length before calling\n-\u0026gt;send() to avoid a use after free.(CVE-2025-22004)\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nposix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()\n\nIf an exiting non-autoreaping task has already passed exit_notify() and\ncalls handle_posix_cpu_timers() from IRQ, it can be reaped by its parent\nor debugger right after unlock_task_sighand().\n\nIf a concurrent posix_cpu_timer_del() runs at that moment, it won\u0026apos;t be\nable to detect timer-\u0026gt;it.cpu.firing != 0: cpu_timer_task_rcu() and/or\nlock_task_sighand() will fail.\n\nAdd the tsk-\u0026gt;exit_state check into run_posix_cpu_timers() to fix this.\n\nThis fix is not needed if CONFIG_POSIX_CPU_TIMERS_TASK_WORK=y, because\nexit_task_work() is called before exit_notify(). But the check still\nmakes sense, task_work_add(\u0026amp;tsk-\u0026gt;posix_cputimers_work.work) will fail\nanyway in this case.(CVE-2025-38352)",
  "id": "OESA-2025-2006",
  "modified": "2026-08-06T11:09:05Z",
  "published": "2025-08-15T11:09:05Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2025-2006"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21920"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21926"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-22004"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38352"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "kernel security update",
  "upstream": [
    "CVE-2025-21920",
    "CVE-2025-21926",
    "CVE-2025-22004",
    "CVE-2025-38352"
  ]
}



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