CVE-2025-38470

Published Jul 28, 2025

Last updated 4 months ago

CVSS medium 5.5

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: net: vlan: fix VLAN 0 refcount imbalance of toggling filtering during runtime Assuming the "rx-vlan-filter" feature is enabled on a net device, the 8021q module will automatically add or remove VLAN 0 when the net device is put administratively up or down, respectively. There are a couple of problems with the above scheme. The first problem is a memory leak that can happen if the "rx-vlan-filter" feature is disabled while the device is running: # ip link add bond1 up type bond mode 0 # ethtool -K bond1 rx-vlan-filter off # ip link del dev bond1 When the device is put administratively down the "rx-vlan-filter" feature is disabled, so the 8021q module will not remove VLAN 0 and the memory will be leaked [1]. Another problem that can happen is that the kernel can automatically delete VLAN 0 when the device is put administratively down despite not adding it when the device was put administratively up since during that time the "rx-vlan-filter" feature was disabled. null-ptr-unref or bug_on[2] will be triggered by unregister_vlan_dev() for refcount imbalance if toggling filtering during runtime: $ ip link add bond0 type bond mode 0 $ ip link add link bond0 name vlan0 type vlan id 0 protocol 802.1q $ ethtool -K bond0 rx-vlan-filter off $ ifconfig bond0 up $ ethtool -K bond0 rx-vlan-filter on $ ifconfig bond0 down $ ip link del vlan0 Root cause is as below: step1: add vlan0 for real_dev, such as bond, team. register_vlan_dev vlan_vid_add(real_dev,htons(ETH_P_8021Q),0) //refcnt=1 step2: disable vlan filter feature and enable real_dev step3: change filter from 0 to 1 vlan_device_event vlan_filter_push_vids ndo_vlan_rx_add_vid //No refcnt added to real_dev vlan0 step4: real_dev down vlan_device_event vlan_vid_del(dev, htons(ETH_P_8021Q), 0); //refcnt=0 vlan_info_rcu_free //free vlan0 step5: delete vlan0 unregister_vlan_dev BUG_ON(!vlan_info); //vlan_info is null Fix both problems by noting in the VLAN info whether VLAN 0 was automatically added upon NETDEV_UP and based on that decide whether it should be deleted upon NETDEV_DOWN, regardless of the state of the "rx-vlan-filter" feature. [1] unreferenced object 0xffff8880068e3100 (size 256): comm "ip", pid 384, jiffies 4296130254 hex dump (first 32 bytes): 00 20 30 0d 80 88 ff ff 00 00 00 00 00 00 00 00 . 0............. 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc 81ce31fa): __kmalloc_cache_noprof+0x2b5/0x340 vlan_vid_add+0x434/0x940 vlan_device_event.cold+0x75/0xa8 notifier_call_chain+0xca/0x150 __dev_notify_flags+0xe3/0x250 rtnl_configure_link+0x193/0x260 rtnl_newlink_create+0x383/0x8e0 __rtnl_newlink+0x22c/0xa40 rtnl_newlink+0x627/0xb00 rtnetlink_rcv_msg+0x6fb/0xb70 netlink_rcv_skb+0x11f/0x350 netlink_unicast+0x426/0x710 netlink_sendmsg+0x75a/0xc20 __sock_sendmsg+0xc1/0x150 ____sys_sendmsg+0x5aa/0x7b0 ___sys_sendmsg+0xfc/0x180 [2] kernel BUG at net/8021q/vlan.c:99! Oops: invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 0 UID: 0 PID: 382 Comm: ip Not tainted 6.16.0-rc3 #61 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:unregister_vlan_dev (net/8021q/vlan.c:99 (discriminator 1)) RSP: 0018:ffff88810badf310 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88810da84000 RCX: ffffffffb47ceb9a RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88810e8b43c8 RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff6cefe80 R10: ffffffffb677f407 R11: ffff88810badf3c0 R12: ffff88810e8b4000 R13: 0000000000000000 R14: ffff88810642a5c0 R15: 000000000000017e FS: 00007f1ff68c20c0(0000) GS:ffff888163a24000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1ff5dad240 CR3: 0000000107e56000 CR4: 00000000000006f0 Call Trace: <TASK ---truncated---
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel, debian_linux

Risk scores

CVSS 3.1

Type
Primary
Base score
5.5
Impact score
3.6
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

nvd@nist.gov
NVD-CWE-Other

Social media

Hype score
Not currently trending

  1. CVE-2025-38470 In the Linux kernel, the following vulnerability has been resolved: net: vlan: fix VLAN 0 refcount imbalance of toggling filtering during runtime Assuming the "rx-v… https://t.co/ZrIQGU9Oz8

    @CVEnew

    28 Jul 2025

    377 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

Configurations

Related CVEs

  1. In the Linux kernel, the following vulnerability has been resolved: net: usb: cdc_ncm: add ndpoffset to NDP32 nframes bounds check The same bounds-check bug fixed for NDP16 in the previous patch also exists in cdc_ncm_rx_verify_ndp32(). The DPE array size is validated against the total skb length without accounting for ndpoffset, allowing out-of-bounds reads when the NDP32 is placed near the end of the NTB. Add ndpoffset to the nframes bounds check and use struct_size_t() to express the NDP-plus-DPE-array size more clearly. Compile-tested only.•CVE-2026-23447
  2. In the Linux kernel, the following vulnerability has been resolved: net: usb: aqc111: Do not perform PM inside suspend callback syzbot reports "task hung in rpm_resume" This is caused by aqc111_suspend calling the PM variant of its write_cmd routine. The simplified call trace looks like this: rpm_suspend() usb_suspend_both() - here udev->dev.power.runtime_status == RPM_SUSPENDING aqc111_suspend() - called for the usb device interface aqc111_write32_cmd() usb_autopm_get_interface() pm_runtime_resume_and_get() rpm_resume() - here we call rpm_resume() on our parent rpm_resume() - Here we wait for a status change that will never happen. At this point we block another task which holds rtnl_lock and locks up the whole networking stack. Fix this by replacing the write_cmd calls with their _nopm variants•CVE-2026-23446
  3. In the Linux kernel, the following vulnerability has been resolved: igc: fix page fault in XDP TX timestamps handling If an XDP application that requested TX timestamping is shutting down while the link of the interface in use is still up the following kernel splat is reported: [ 883.803618] [ T1554] BUG: unable to handle page fault for address: ffffcfb6200fd008 ... [ 883.803650] [ T1554] Call Trace: [ 883.803652] [ T1554] <TASK> [ 883.803654] [ T1554] igc_ptp_tx_tstamp_event+0xdf/0x160 [igc] [ 883.803660] [ T1554] igc_tsync_interrupt+0x2d5/0x300 [igc] ... During shutdown of the TX ring the xsk_meta pointers are left behind, so that the IRQ handler is trying to touch them. This issue is now being fixed by cleaning up the stale xsk meta data on TX shutdown. TX timestamps on other queues remain unaffected.•CVE-2026-23445
  4. In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: always free skb on ieee80211_tx_prepare_skb() failure ieee80211_tx_prepare_skb() has three error paths, but only two of them free the skb. The first error path (ieee80211_tx_prepare() returning TX_DROP) does not free it, while invoke_tx_handlers() failure and the fragmentation check both do. Add kfree_skb() to the first error path so all three are consistent, and remove the now-redundant frees in callers (ath9k, mt76, mac80211_hwsim) to avoid double-free. Document the skb ownership guarantee in the function's kdoc.•CVE-2026-23444
  5. In the Linux kernel, the following vulnerability has been resolved: ACPI: processor: Fix previous acpi_processor_errata_piix4() fix After commi f132e089fe89 ("ACPI: processor: Fix NULL-pointer dereference in acpi_processor_errata_piix4()"), device pointers may be dereferenced after dropping references to the device objects pointed to by them, which may cause a use-after-free to occur. Moreover, debug messages about enabling the errata may be printed if the errata flags corresponding to them are unset. Address all of these issues by moving message printing to the points in the code where the errata flags are set.•CVE-2026-23443

References

Sources include official advisories and independent security research.