Describe CVE-2021-47160.
What is CVE-2021-47160?
In the Linux kernel, the following vulnerability has been resolved:

net: dsa: mt7530: fix VLAN traffic leaks

PCR_MATRIX field was set to all 1's when VLAN filtering is enabled, but
was not reset when it is disabled, which may cause traffic leaks:

	ip link add br0 type bridge vlan_filtering 1
	ip link add br1 type bridge vlan_filtering 1
	ip link set swp0 master br0
	ip link set swp1 master br1
	ip link set br0 type bridge vlan_filtering 0
	ip link set br1 type bridge vlan_filtering 0
	# traffic in br0 and br1 will start leaking to each other

As port_bridge_{add,del} have set up PCR_MATRIX properly, remove the
PCR_MATRIX write from mt7530_port_set_vlan_aware..