vde_switch crashes if vlan # 0 is removed #23
Description
In older versions of vde2 the following switch startup configuration worked like a charm:
vlan/create 1 # isolated w/o real network access
vlan/create 2 # access to local samba server
vlan/create 3 # bridged to hypervisor
port/setvlan 1 1
port/setvlan 2 3
port/create 3
port/setvlan 3 2
vlan/remove 0
In other words, I set up 3 new VLANs and then removed the default VLAN # 0.
I did this because this default VLAN seemed to be special in that it was exempt from VLAN filtering and could therefore see all the traffic. I considered that a security risk and therefore deleted the VLAN.
However, current versions of vde_switch crash when adding new ports after VLAN # 0 has been removed.
Core dump analysis shows the crash happens in line 170 of file src/vde_switch/port.c where the expression
ba_set(vlant[0].table,i)
is evaluated with vlant[0].table containing a null pointer.
Suggested course of action: Either the code should check whether vlant[0].table contains a null pointer and then avoid dereferencing it, or removal of VLAN # 0 should be forbidden because then there will not be a null pointer.