CVE-2025-38470

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 bugon[2] will be triggered by unregistervlan_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 realdev, such as bond, team. registervlandev vlanvidadd(realdev,htons(ETHP8021Q),0) //refcnt=1 step2: disable vlan filter feature and enable realdev step3: change filter from 0 to 1 vlandeviceevent vlanfilterpushvids ndovlanrxaddvid //No refcnt added to realdev vlan0 step4: realdev down vlandeviceevent vlanviddel(dev, htons(ETHP8021Q), 0); //refcnt=0 vlaninforcufree //free vlan0 step5: delete vlan0 unregistervlandev BUGON(!vlaninfo); //vlaninfo is null

Fix both problems by noting in the VLAN info whether VLAN 0 was automatically added upon NETDEVUP and based on that decide whether it should be deleted upon NETDEVDOWN, 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): kmalloccachenoprof+0x2b5/0x340 vlanvidadd+0x434/0x940 vlandeviceevent.cold+0x75/0xa8 notifiercallchain+0xca/0x150 _devnotifyflags+0xe3/0x250 rtnlconfigurelink+0x193/0x260 rtnlnewlinkcreate+0x383/0x8e0 _rtnlnewlink+0x22c/0xa40 rtnlnewlink+0x627/0xb00 rtnetlinkrcvmsg+0x6fb/0xb70 netlinkrcvskb+0x11f/0x350 netlinkunicast+0x426/0x710 netlinksendmsg+0x75a/0xc20 _socksendmsg+0xc1/0x150 syssendmsg+0x5aa/0x7b0 _syssendmsg+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:unregistervlandev (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---

References

Affected packages

Debian:11 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

5.*

5.10.46-4

5.10.46-5

5.10.70-1~bpo10+1

5.10.70-1

5.10.84-1

5.10.92-1~bpo10+1

5.10.92-1

5.10.92-2

5.10.103-1~bpo10+1

5.10.103-1

5.10.106-1

5.10.113-1

5.10.120-1~bpo10+1

5.10.120-1

5.10.127-1

5.10.127-2~bpo10+1

5.10.127-2

5.10.136-1

5.10.140-1

5.10.148-1

5.10.149-1

5.10.149-2

5.10.158-1

5.10.158-2

5.10.162-1

5.10.178-1

5.10.178-2

5.10.178-3

5.10.179-1

5.10.179-2

5.10.179-3

5.10.179-4

5.10.179-5

5.10.191-1

5.10.197-1

5.10.205-1

5.10.205-2

5.10.209-1

5.10.209-2

5.10.216-1

5.10.218-1

5.10.221-1

5.10.223-1

5.10.226-1

5.10.234-1

5.10.237-1

5.13.9-1~exp1

5.13.9-1~exp2

5.13.12-1~exp1

5.14-1~exp1

5.14-1~exp2

5.14.1-1~exp1

5.14.2-1~exp1

5.14.3-1~exp1

5.14.6-1

5.14.6-2

5.14.6-3

5.14.9-1

5.14.9-2~bpo11+1

5.14.9-2

5.14.12-1

5.14.16-1

5.15-1~exp1

5.15.1-1~exp1

5.15.2-1~exp1

5.15.3-1

5.15.5-1

5.15.5-2~bpo11+1

5.15.5-2

5.15.15-1

5.15.15-2~bpo11+1

5.15.15-2

5.16~rc1-1~exp1

5.16~rc3-1~exp1

5.16~rc4-1~exp1

5.16~rc5-1~exp1

5.16~rc6-1~exp1

5.16~rc7-1~exp1

5.16~rc8-1~exp1

5.16.3-1~exp1

5.16.4-1~exp1

5.16.7-1

5.16.7-2

5.16.10-1

5.16.11-1~bpo11+1

5.16.11-1

5.16.12-1~bpo11+1

5.16.12-1

5.16.14-1

5.16.18-1

5.17~rc3-1~exp1

5.17~rc4-1~exp1

5.17~rc5-1~exp1

5.17~rc6-1~exp1

5.17~rc7-1~exp1

5.17~rc8-1~exp1

5.17.1-1~exp1

5.17.3-1

5.17.6-1

5.17.11-1

5.18-1~exp1

5.18.2-1~bpo11+1

5.18.2-1

5.18.5-1

5.18.14-1~bpo11+1

5.18.14-1

5.18.16-1~bpo11+1

5.18.16-1

5.19~rc4-1~exp1

5.19~rc6-1~exp1

5.19-1~exp1

5.19.6-1

5.19.11-1~bpo11+1

5.19.11-1

6.*

6.0~rc7-1~exp1

6.0-1~exp1

6.0.2-1

6.0.3-1~bpo11+1

6.0.3-1

6.0.5-1

6.0.6-1

6.0.6-2

6.0.7-1

6.0.8-1

6.0.10-1

6.0.10-2

6.0.12-1~bpo11+1

6.0.12-1

6.0.12-1+alpha

6.1~rc3-1~exp1

6.1~rc5-1~exp1

6.1~rc6-1~exp1

6.1~rc7-1~exp1

6.1~rc8-1~exp1

6.1.1-1~exp1

6.1.1-1~exp2

6.1.2-1~exp1

6.1.4-1

6.1.7-1

6.1.8-1

6.1.8-1+sh4

6.1.11-1

6.1.12-1~bpo11+1

6.1.12-1

6.1.15-1~bpo11+1

6.1.15-1

6.1.20-1~bpo11+1

6.1.20-1

6.1.20-2~bpo11+1

6.1.20-2

6.1.25-1

6.1.27-1~bpo11+1

6.1.27-1

6.1.37-1

6.1.38-1

6.1.38-2~bpo11+1

6.1.38-2

6.1.38-3

6.1.38-4~bpo11+1

6.1.38-4

6.1.52-1

6.1.55-1~bpo11+1

6.1.55-1

6.1.64-1

6.1.66-1

6.1.67-1

6.1.69-1~bpo11+1

6.1.69-1

6.1.76-1~bpo11+1

6.1.76-1

6.1.82-1

6.1.85-1

6.1.90-1~bpo11+1

6.1.90-1

6.1.94-1~bpo11+1

6.1.94-1

6.1.98-1

6.1.99-1

6.1.106-1

6.1.106-2

6.1.106-3

6.1.112-1

6.1.115-1

6.1.119-1

6.1.123-1

6.1.124-1

6.1.128-1

6.1.129-1

6.1.133-1

6.1.135-1

6.1.137-1

6.1.139-1

6.1.140-1

6.1.147-1

6.3.1-1~exp1

6.3.2-1~exp1

6.3.4-1~exp1

6.3.5-1~exp1

6.3.7-1~bpo12+1

6.3.7-1

6.3.11-1

6.4~rc6-1~exp1

6.4~rc7-1~exp1

6.4.1-1~exp1

6.4.4-1~bpo12+1

6.4.4-1

6.4.4-2

6.4.4-3~bpo12+1

6.4.4-3

6.4.11-1

6.4.13-1

6.5~rc4-1~exp1

6.5~rc6-1~exp1

6.5~rc7-1~exp1

6.5.1-1~exp1

6.5.3-1~bpo12+1

6.5.3-1

6.5.6-1

6.5.8-1

6.5.10-1~bpo12+1

6.5.10-1

6.5.13-1

6.6.3-1~exp1

6.6.4-1~exp1

6.6.7-1~exp1

6.6.8-1

6.6.9-1

6.6.11-1

6.6.13-1~bpo12+1

6.6.13-1

6.6.15-1

6.6.15-2

6.7-1~exp1

6.7.1-1~exp1

6.7.4-1~exp1

6.7.7-1

6.7.9-1

6.7.9-2

6.7.12-1~bpo12+1

6.7.12-1

6.8.9-1

6.8.11-1

6.8.12-1~bpo12+1

6.8.12-1

6.9.2-1~exp1

6.9.7-1~bpo12+1

6.9.7-1

6.9.8-1

6.9.9-1

6.9.10-1~bpo12+1

6.9.10-1

6.9.11-1

6.9.12-1

6.10-1~exp1

6.10.1-1~exp1

6.10.3-1

6.10.4-1

6.10.6-1~bpo12+1

6.10.6-1

6.10.7-1

6.10.9-1

6.10.11-1~bpo12+1

6.10.11-1

6.10.12-1

6.11~rc4-1~exp1

6.11~rc5-1~exp1

6.11-1~exp1

6.11.2-1

6.11.4-1

6.11.5-1~bpo12+1

6.11.5-1

6.11.6-1

6.11.7-1

6.11.9-1

6.11.10-1~bpo12+1

6.11.10-1

6.12~rc6-1~exp1

6.12.3-1

6.12.5-1

6.12.6-1

6.12.8-1

6.12.9-1~bpo12+1

6.12.9-1

6.12.9-1+alpha

6.12.10-1

6.12.11-1

6.12.11-1+alpha

6.12.11-1+alpha.1

6.12.12-1~bpo12+1

6.12.12-1

6.12.13-1

6.12.15-1

6.12.16-1

6.12.17-1

6.12.19-1

6.12.20-1

6.12.21-1

6.12.22-1~bpo12+1

6.12.22-1

6.12.25-1

6.12.27-1~bpo12+1

6.12.27-1

6.12.29-1

6.12.30-1~bpo12+1

6.12.30-1

6.12.31-1

6.12.32-1~bpo12+1

6.12.32-1

6.12.33-1~bpo12+1

6.12.33-1

6.12.35-1~bpo12+1

6.12.35-1

6.12.37-1

6.12.38-1~bpo12+1

6.12.38-1

6.13~rc6-1~exp1

6.13~rc7-1~exp1

6.13.2-1~exp1

6.13.3-1~exp1

6.13.4-1~exp1

6.13.5-1~exp1

6.13.6-1~exp1

6.13.7-1~exp1

6.13.8-1~exp1

6.13.9-1~exp1

6.13.10-1~exp1

6.13.11-1~exp1

6.14.3-1~exp1

6.14.5-1~exp1

6.14.6-1~exp1

6.15~rc7-1~exp1

6.15-1~exp1

6.15.1-1~exp1

6.15.2-1~exp1

6.15.3-1~exp1

6.15.4-1~exp1

6.15.5-1~exp1

6.15.6-1~exp1

6.16~rc7-1~exp1

6.16-1~exp1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Debian:12 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

6.1.147-1

Affected versions

6.*

6.1.27-1

6.1.37-1

6.1.38-1

6.1.38-2~bpo11+1

6.1.38-2

6.1.38-3

6.1.38-4~bpo11+1

6.1.38-4

6.1.52-1

6.1.55-1~bpo11+1

6.1.55-1

6.1.64-1

6.1.66-1

6.1.67-1

6.1.69-1~bpo11+1

6.1.69-1

6.1.76-1~bpo11+1

6.1.76-1

6.1.82-1

6.1.85-1

6.1.90-1~bpo11+1

6.1.90-1

6.1.94-1~bpo11+1

6.1.94-1

6.1.98-1

6.1.99-1

6.1.106-1

6.1.106-2

6.1.106-3

6.1.112-1

6.1.115-1

6.1.119-1

6.1.123-1

6.1.124-1

6.1.128-1

6.1.129-1

6.1.133-1

6.1.135-1

6.1.137-1

6.1.139-1

6.1.140-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Debian:13 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

6.12.41-1

Affected versions

6.*

6.12.38-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Debian:14 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

6.*

6.12.38-1

6.13~rc6-1~exp1

6.13~rc7-1~exp1

6.13.2-1~exp1

6.13.3-1~exp1

6.13.4-1~exp1

6.13.5-1~exp1

6.13.6-1~exp1

6.13.7-1~exp1

6.13.8-1~exp1

6.13.9-1~exp1

6.13.10-1~exp1

6.13.11-1~exp1

6.14.3-1~exp1

6.14.5-1~exp1

6.14.6-1~exp1

6.15~rc7-1~exp1

6.15-1~exp1

6.15.1-1~exp1

6.15.2-1~exp1

6.15.3-1~exp1

6.15.4-1~exp1

6.15.5-1~exp1

6.15.6-1~exp1

6.16~rc7-1~exp1

6.16-1~exp1

Ecosystem specific

{
    "urgency": "not yet assigned"
}