I have just downloaded the latest gr-ieee802-11, recompiled and reinstalled.
I am using the latest version of the flowgraph. Just that the gnuradio was the one installed at January 2015.
Below is the debugging message.
(gdb) run wifi_loopback.py
Starting program: /usr/bin/python wifi_loopback.py
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/i386-linux-gnu/i686/cmov/libthread_db.so.1".
linux; GNU C++ version 4.7.2; Boost_104900; UHD_003.008.001-121-gebe7169d
[New Thread 0xaecc0b70 (LWP 4846)]
[New Thread 0xad5c1b70 (LWP 4847)]
Using Volk machine: avx_32_mmx_orc
[New Thread 0xa668cb70 (LWP 4848)]
OFDM MAPPER: encoding: 0
set_min_output_buffer on block 31 to 96000
set_min_output_buffer on block 33 to 96000
set_min_output_buffer on block 35 to 96000
set_min_output_buffer on block 36 to 96000
set_min_output_buffer on block 39 to 96000
set_min_output_buffer on block 50 to 96000
[New Thread 0xa397ab70 (LWP 4849)]
[New Thread 0x95dd8b70 (LWP 4850)]
[New Thread 0x955d7b70 (LWP 4851)]
[New Thread 0x94dd6b70 (LWP 4852)]
[New Thread 0x945d5b70 (LWP 4853)]
[New Thread 0x93dd4b70 (LWP 4854)]
[New Thread 0x935d3b70 (LWP 4855)]
[New Thread 0x92dd2b70 (LWP 4856)]
[New Thread 0x925d1b70 (LWP 4857)]
[New Thread 0x91dd0b70 (LWP 4858)]
[New Thread 0x915cfb70 (LWP 4859)]
[New Thread 0x90dceb70 (LWP 4860)]
[New Thread 0x905cdb70 (LWP 4861)]
[New Thread 0x8fdccb70 (LWP 4862)]
[New Thread 0x8f5cbb70 (LWP 4863)]
[New Thread 0x8edcab70 (LWP 4864)]
[New Thread 0x8e5c9b70 (LWP 4865)]
[New Thread 0x8ddc8b70 (LWP 4866)]
[New Thread 0x8d5c7b70 (LWP 4867)]
[New Thread 0x8cdc6b70 (LWP 4868)]
[New Thread 0x8c5c5b70 (LWP 4869)]
[New Thread 0x8bdc4b70 (LWP 4870)]
[New Thread 0x8b5c3b70 (LWP 4871)]
[New Thread 0x8adc2b70 (LWP 4872)]
[New Thread 0x8a5c1b70 (LWP 4873)]
[New Thread 0x89dc0b70 (LWP 4874)]
[New Thread 0x895bfb70 (LWP 4875)]
[New Thread 0x88dbeb70 (LWP 4876)]
[New Thread 0x885bdb70 (LWP 4877)]
[New Thread 0x87dbcb70 (LWP 4878)]
[New Thread 0x875bbb70 (LWP 4879)]
[New Thread 0x86dbab70 (LWP 4880)]
[New Thread 0x865b9b70 (LWP 4881)]
[New Thread 0x85db8b70 (LWP 4882)]
[New Thread 0x855b7b70 (LWP 4883)]
[New Thread 0x84db6b70 (LWP 4884)]
[New Thread 0x845b5b70 (LWP 4885)]
[New Thread 0x83db4b70 (LWP 4886)]
[New Thread 0x835b3b70 (LWP 4887)]
[New Thread 0x82db2b70 (LWP 4888)]
[New Thread 0x825b1b70 (LWP 4889)]
[New Thread 0x81db0b70 (LWP 4890)]
[New Thread 0x815afb70 (LWP 4891)]
[New Thread 0x80daeb70 (LWP 4892)]
[New Thread 0x805adb70 (LWP 4893)]
[New Thread 0x7fdacb70 (LWP 4894)]
[New Thread 0x7f5abb70 (LWP 4895)]
[New Thread 0x7edaab70 (LWP 4896)]
[New Thread 0x7e5a9b70 (LWP 4897)]
[New Thread 0x7dda8b70 (LWP 4898)]
[New Thread 0x7d5a7b70 (LWP 4899)]
[New Thread 0x7cda6b70 (LWP 4900)]
[New Thread 0x7c5a5b70 (LWP 4901)]
[New Thread 0x7bda4b70 (LWP 4902)]
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x815afb70 (LWP 4891)]
0xb2fc302e in ofdm_decode_signal_impl::general_work(int, std::vector<int, std::allocator<int> >&, std::vector<void const*, std::allocator<void const*> >&, std::vector<void*, std::allocator<void*> >&) ()
from /usr/local/lib/libgnuradio-ieee802_11.so
(gdb)