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
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade perf-debuginfoUpgrade kernel-tools-develUpgrade perfUpgrade python-perf-debuginfoUpgrade kernel-livepatch-5.10.157-139.675Upgrade kernel-debuginfo-common-aarch64Upgrade kernel-livepatch-5.15.86-53.137Upgrade kernel-toolsUpgrade kernel-headersUpgrade kernel-tools-debuginfoUpgrade bpftool-debuginfoUpgrade bpftoolUpgrade kernel-develUpgrade kernelUpgrade python-perfUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-debuginfo | Jun 23, 2025 | May 1, 2025 |
| Debian | — | Upgrade linux | May 5, 2025 | May 1, 2025 |
| Huawei Euleros 2_0_sp13 | — | Upgrade bpftoolUpgrade kernelUpgrade kernel-tools-libsUpgrade kernel-abi-stablelistsUpgrade kernel-toolsUpgrade python3-perf | Oct 24, 2025 | Oct 23, 2025 |
| Redhat_linux | — | No solution exists | Jul 9, 2025 | May 1, 2025 |
| Ubuntu | — | Upgrade linux-awsUpgrade linux-aws-5.15Upgrade linux-bluefieldUpgrade linux-nvidia-tegra-5.15Upgrade linuxUpgrade linux-hwe-5.15Upgrade linux-azureUpgrade linux-raspiUpgrade linux-gcp-5.15Upgrade linux-intel-iot-realtimeUpgrade linux-realtimeUpgrade linux-azure-5.15Upgrade linux-nvidiaUpgrade linux-intel-iotg-5.15Upgrade linux-lowlatency-hwe-5.15Upgrade linux-kvmUpgrade linux-gkeopUpgrade linux-lowlatencyUpgrade linux-gkeUpgrade linux-oracle-5.15Upgrade linux-ibmUpgrade linux-gcpUpgrade linux-oracleUpgrade linux-riscv-5.15Upgrade linux-intel-iotg | 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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