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
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade bpftool-debuginfoUpgrade kernel-tools-debuginfoUpgrade kernel-develUpgrade kernelUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-debuginfoUpgrade bpftoolUpgrade python-perfUpgrade kernel-livepatch-5.10.157-139.675Upgrade kernel-debuginfo-common-aarch64Upgrade kernel-tools-develUpgrade python-perf-debuginfoUpgrade perfUpgrade kernel-toolsUpgrade perf-debuginfoUpgrade kernel-livepatch-5.15.86-53.137Upgrade kernel-headers | Jun 23, 2025 | May 1, 2025 |
| Debian | — | Upgrade linux | May 5, 2025 | May 1, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade kernel-tools-libsUpgrade kernel-abi-stablelistsUpgrade kernel-toolsUpgrade kernelUpgrade bpftoolUpgrade python3-perf | Oct 24, 2025 | Oct 23, 2025 |
| Redhat_linux | — | No solution exists | Jul 9, 2025 | May 1, 2025 |
| Ubuntu | — | Upgrade linux-kvmUpgrade linux-oracle-5.15Upgrade linux-gkeopUpgrade linux-lowlatencyUpgrade linux-intel-iotgUpgrade linux-nvidiaUpgrade linux-ibmUpgrade linux-gkeUpgrade linux-gcpUpgrade linux-riscv-5.15Upgrade linux-lowlatency-hwe-5.15Upgrade linux-azure-fdeUpgrade linux-gcp-5.15Upgrade linux-realtimeUpgrade linux-intel-iotg-5.15Upgrade linux-intel-iot-realtimeUpgrade linux-azure-5.15Upgrade linux-oracleUpgrade linux-bluefieldUpgrade linux-hwe-5.15Upgrade linux-awsUpgrade linuxUpgrade linux-azureUpgrade linux-aws-5.15Upgrade linux-raspiUpgrade linux-nvidia-tegra-5.15 | May 8, 2025 | May 1, 2025 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | May 1, 2025 |
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