Linux Kernel Bridge Driver VLAN Offload Memory Leak Vulnerability

A vulnerability in the Linux kernel's bridge driver can lead to memory leaks when managing VLAN protocols. This issue arises during the offloading of VLANs to hardware via switchdev, which is not properly synchronized with the 8021q driver, causing redundant operations and memory management errors. The vulnerability affects several Linux kernel versions.

Impact

Exploitation of this vulnerability can lead to memory leaks in the bridge driver, causing unreferenced objects to remain in memory and potentially leading to degraded system performance or stability.

Reproduction

The vulnerability can be reproduced by offloading VLANs to hardware using the switchdev method, and then changing the VLAN protocol. This will trigger a notification to the switchdev driver, which should handle the protocol change. However, the 8021q driver is also called, leading to a memory leak when VLANs are deleted, especially if they were offloaded via switchdev.