CVE-2022-49234

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

net: dsa: Avoid cross-chip syncing of VLAN filtering

Changes to VLAN filtering are not applicable to cross-chip notifications.

On a system like this:

.-----. .-----. .-----. | sw1 +---+ sw2 +---+ sw3 | '-1-2-' '-1-2-' '-1-2-'

Before this change, upon sw1p1 leaving a bridge, a call to dsa_port_vlan_filtering would also be made to sw2p1 and sw3p1.

In this scenario:

.---------. .-----. .-----. | sw1 +---+ sw2 +---+ sw3 | '-1-2-3-4-' '-1-2-' '-1-2-'

When sw1p4 would leave a bridge, dsa_port_vlan_filtering would be called for sw2 and sw3 with a non-existing port - leading to array out-of-bounds accesses and crashes on mv88e6xxx.

This vulnerability does not affect supported Red Hat Enterprise Linux releases as the vulnerable code paths are not present in enterprise kernels. The underlying issue exists in the kernel's Distributed Switch Architecture subsystem when propagating bridge VLAN filtering across multi-chip switch fabrics, which can trigger an out-of-bounds access. Exploitation necessitates specialized physical network switch hardware topologies that are uncharacteristic of standard enterprise server deployments.