illumos gate

If you specify the same field more than once it causes a segfault:

# dladm show-link -o link,class,mtu,state,bridge,over,link
dladm: warning: Not enough space
Segmentation Fault (core dumped)

# dladm show-link -o class,mtu,state,bridge,over,link
CLASS     MTU    STATE    BRIDGE     OVER                          LINK
phys      1500   up       --         --                            e1000g0
phys      1500   down     --         --                            ixgbe0

# dladm show-link -o link,class,mtu,state,bridge,over,over
dladm: warning: Not enough space
Segmentation Fault (core dumped)

The failure mode here is slightly tighter in that dladm (and friends) die if you specify more fields than there are fields – which tautologically means that you have specified at least one field at least twice. e.g.:

# dladm show-link -o class,class,class,class,class
CLASS     CLASS     CLASS     CLASS     CLASS
vnic      vnic      vnic      vnic      vnic
vnic      vnic      vnic      vnic      vnic
# dladm show-link -o class,class,class,class,class,class,class
dladm: warning: Not enough space
Segmentation Fault (core dumped)

There are actually two problems here: one is that it is failing (with an out-of-memory error) the other is that the resulting out-of-memory error isn't properly handled (inducing the seg fault).