CVE-2022-49812 bridge: switchdev: Fix memory leaks when changing VLAN protocol

What is CVE-2022-49812?

CVE-2022-49812 is a medium-severity memory corruption vulnerability in Linux kernel, published on 1 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

bridge: switchdev: Fix memory leaks when changing VLAN protocol

The bridge driver can offload VLANs to the underlying hardware either via switchdev or the 8021q driver. When the former is used, the VLAN is marked in the bridge driver with the 'BR_VLFLAG_ADDED_BY_SWITCHDEV' private flag.

To avoid the memory leaks mentioned in the cited commit, the bridge driver will try to delete a VLAN via the 8021q driver if the VLAN is not marked with the previously mentioned flag.

When the VLAN protocol of the bridge changes, switchdev drivers are notified via the 'SWITCHDEV_ATTR_ID_BRIDGE_VLAN_PROTOCOL' attribute, but the 8021q driver is also called to add the existing VLANs with the new protocol and delete them with the old protocol.

In case the VLANs were offloaded via switchdev, the above behavior is both redundant and buggy. Redundant because the VLANs are already programmed in hardware and drivers that support VLAN protocol change (currently only mlx5) change the protocol upon the switchdev attribute notification. Buggy because the 8021q driver is called despite these VLANs being marked with 'BR_VLFLAG_ADDED_BY_SWITCHDEV'. This leads to memory leaks [1] when the VLANs are deleted.

Fix by not calling the 8021q driver for VLANs that were already programmed via switchdev.

[1] unreferenced object 0xffff8881f6771200 (size 256): comm "ip", pid 446855, jiffies 4298238841 (age 55.240s) hex dump (first 32 bytes): 00 00 7f 0e 83 88 ff ff 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000012819ac>] vlan_vid_add+0x437/0x750 [<00000000f2281fad>] __br_vlan_set_proto+0x289/0x920 [<000000000632b56f>] br_changelink+0x3d6/0x13f0 [<0000000089d25f04>] __rtnl_newlink+0x8ae/0x14c0 [<00000000f6276baf>] rtnl_newlink+0x5f/0x90 [<00000000746dc902>] rtnetlink_rcv_msg+0x336/0xa00 [<000000001c2241c0>] netlink_rcv_skb+0x11d/0x340 [<0000000010588814>] netlink_unicast+0x438/0x710 [<00000000e1a4cd5c>] netlink_sendmsg+0x788/0xc40 [<00000000e8992d4e>] sock_sendmsg+0xb0/0xe0 [<00000000621b8f91>] ____sys_sendmsg+0x4ff/0x6d0 [<000000000ea26996>] ___sys_sendmsg+0x12e/0x1b0 [<00000000684f7e25>] __sys_sendmsg+0xab/0x130 [<000000004538b104>] do_syscall_64+0x3d/0x90 [<0000000091ed9678>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

Weakness: CWE-401

Which versions are affected by CVE-2022-49812?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2022-49812?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2022-49812 being exploited?

There is no known exploitation of CVE-2022-49812 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2022-49812, GHSA-9x8c-4rx4-5mxv, UBUNTU-CVE-2022-49812.