prov/sockets: use after free

[shefty]

caught by CI on OS X
https://travis-ci.org/github/ofiwg/libfabric/builds/704164676

name: fi_shared_ctx -p "sockets"
result: Fail
time: 3
server_cmd: fi_shared_ctx -p "sockets" -s 127.0.0.1
server_stdout: |
=================================================================
==94143==ERROR: AddressSanitizer: heap-use-after-free on address 0x6270000072e0 at pc 0x000105ed963c bp 0x700008c1fc30 sp 0x700008c1fc28
READ of size 4 at 0x6270000072e0 thread T2
#0 0x105ed963b in sock_conn_listener_thread (libfabric.1.dylib:x86_64+0xdc63b)
#1 0x7fff5882e660 in _pthread_body (libsystem_pthread.dylib:x86_64+0x3660)
#2 0x7fff5882e50c in _pthread_start (libsystem_pthread.dylib:x86_64+0x350c)
#3 0x7fff5882dbf8 in thread_start (libsystem_pthread.dylib:x86_64+0x2bf8)

0x6270000072e0 is located 480 bytes inside of 12944-byte region [0x627000007100,0x62700000a390)
freed by thread T0 here:
    #0 0x1060a3a9d in wrap_free (libclang_rt.asan_osx_dynamic.dylib:x86_64+0x56a9d)
    #1 0x105eb42cf in sock_ep_close (libfabric.1.dylib:x86_64+0xb72cf)
    #2 0x105dabbff in fi_close fabric.h:589
    #3 0x105dab38c in main shared_ctx.c:649
    #4 0x7fff58516014 in start (libdyld.dylib:x86_64+0x1014)

previously allocated by thread T0 here:
    #0 0x1060a3e27 in wrap_calloc (libclang_rt.asan_osx_dynamic.dylib:x86_64+0x56e27)
    #1 0x105eb9a04 in sock_alloc_endpoint (libfabric.1.dylib:x86_64+0xbca04)
    #2 0x105ea7b19 in sock_rdm_ep (libfabric.1.dylib:x86_64+0xaab19)
    #3 0x105daee03 in fi_endpoint fi_endpoint.h:164
    #4 0x105dae914 in alloc_ep shared_ctx.c:123
    #5 0x105dadd45 in init_fabric shared_ctx.c:340
    #6 0x105dabb3d in run shared_ctx.c:575
    #7 0x105dab29e in main shared_ctx.c:647
    #8 0x7fff58516014 in start (libdyld.dylib:x86_64+0x1014)

Thread T2 created by T0 here:
    #0 0x10609b99d in wrap_pthread_create (libclang_rt.asan_osx_dynamic.dylib:x86_64+0x4e99d)
    #1 0x105ed8b9b in sock_conn_start_listener_thread (libfabric.1.dylib:x86_64+0xdbb9b)
    #2 0x105e9aac2 in sock_domain (libfabric.1.dylib:x86_64+0x9dac2)
    #3 0x105db2193 in fi_domain fi_domain.h:286
    #4 0x105db1f7f in ft_open_fabric_res shared.c:520
    #5 0x105dadc74 in init_fabric shared_ctx.c:330
    #6 0x105dabb3d in run shared_ctx.c:575
    #7 0x105dab29e in main shared_ctx.c:647
    #8 0x7fff58516014 in start (libdyld.dylib:x86_64+0x1014)

SUMMARY: AddressSanitizer: heap-use-after-free (libfabric.1.dylib:x86_64+0xdc63b) in sock_conn_listener_thread
Shadow bytes around the buggy address:
  0x1c4e00000e00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x1c4e00000e10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x1c4e00000e20: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c4e00000e30: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c4e00000e40: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
=>0x1c4e00000e50: fd fd fd fd fd fd fd fd fd fd fd fd[fd]fd fd fd
  0x1c4e00000e60: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c4e00000e70: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c4e00000e80: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c4e00000e90: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x1c4e00000ea0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==94143==ABORTING
Posting recv #0 for shared rx ctx
Posting recv #1 for shared rx ctx
Posting recv #2 for shared rx ctx
Posting recv #3 for shared rx ctx
Posting send #0 to shared tx ctx
Posting send #1 to shared tx ctx
Posting send #2 to shared tx ctx
Posting send #3 to shared tx ctx
./scripts/runfabtests.sh: line 434: 94142 Abort trap: 6           timeout 120 fi_shared_ctx -p "sockets" -s 127.0.0.1