Segmentation faults with scheduler RTPS and onOffApplication.

- Repo: http://code.nsnam.org/ns-3-dev/ (r6144)

- Simulation (variation of wimax-simple with OnOffaplication with 2 flows: SS1->SS0 and SS2->SS0):

http://109.74.199.145/public/wimax-onoff.cc

- Execution:

NS_LOG="PacketSink=level_all|prefix_time" ./waf --run "scratch/wimax-onoff --scheduler=2"

- Output (last lines):

1.22815s Received 256 bytes from 10.1.1.2 [05-06-0a:01:01:02:01:c0] total Rx 6400
1.23776s PacketSink:HandleRead(0x8113868, 0x8131008)
1.23776s Received 256 bytes from 10.1.1.2 [05-06-0a:01:01:02:01:c0] total Rx 6656
1.23776s PacketSink:HandleRead(0x8113868, 0x8131008)
1.23776s Received 256 bytes from 10.1.1.3 [05-06-0a:01:01:03:01:c0] total Rx 6912
Command ['/home/arnau/ehas/ns-3-dev/build/debug/scratch/wimax-simple', '--scheduler=2'] exited with code -11

- Traceback:

(gdb) where
#0  0x00007ffff725e9a2 in ns3::Buffer::GetSize (this=0x8) at ../src/common/buffer.h:639
#1  0x00007ffff7280022 in ns3::Packet::GetSize (this=0x0) at ../src/common/packet.h:621
#2  0x00007ffff797c62e in ns3::PacketBurst::GetSize (this=0x739e10)
    at ../src/devices/wimax/packet-burst.cc:102
#3  0x00007ffff795b306 in ns3::BaseStationNetDevice::SendBursts (this=0x707020)
    at ../src/devices/wimax/bs-net-device.cc:975
#4  0x00007ffff7956713 in ns3::BaseStationNetDevice::StartDlSubFrame (this=0x707020)
    at ../src/devices/wimax/bs-net-device.cc:545
#5  0x00007ffff79564ba in ns3::BaseStationNetDevice::StartFrame (this=0x707020)
    at ../src/devices/wimax/bs-net-device.cc:529
#6  0x00007ffff7956bec in ns3::BaseStationNetDevice::EndFrame (this=0x707020)
    at ../src/devices/wimax/bs-net-device.cc:585
#7  0x00007ffff795f3fc in Notify (this=0x73a710) at debug/ns3/make-event.h:88
#8  0x00007ffff720d59c in ns3::EventImpl::Invoke (this=0x73a710)
    at ../src/simulator/event-impl.cc:37
#9  0x00007ffff722a938 in ns3::DefaultSimulatorImpl::ProcessOneEvent (this=0x651970)
    at ../src/simulator/default-simulator-impl.cc:128
#10 0x00007ffff722aada in ns3::DefaultSimulatorImpl::Run (this=0x651970)