net: mscc: ocelot: fix use-after-free in ocelot_vlan_del()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: mscc: ocelot: fix use-after-free in ocelot_vlan_del() ocelot_vlan_member_del() will free the struct ocelot_bridge_vlan, so if this is the same as the port's pvid_vlan which we access afterwards, what we're accessing is freed memory. Fix the bug by determining whether to clear ocelot_port->pvid_vlan prior to calling ocelot_vlan_member_del().

References

• https://git.kernel.org/stable/c/c98bed60cdd7f22237ae256cc9c1c3087206b8a2
• https://git.kernel.org/stable/c/ef57640575406f57f5b3393cf57f457b0ace837e