Description:
First, I was connected to my home wireless network. Without killing dhcpcd, I moved out of its range and then tried to connect to a different wireless network. In doing so, I killed dhcpcd and ran it on wlan0 again, which resulted in the following trace from glib:

dhcpcd[18140]: version 5.5.5 starting
dhcpcd[18140]: wlan0: sending IPv6 Router Solicitation
dhcpcd[18140]: wlan0: rebinding lease of 192.168.1.39
dhcpcd[18140]: wlan0: NAK: requested address not available from 172.19.34.4
*** glibc detected *** dhcpcd: double free or corruption (fasttop): 0x0000000002056860 ***
======= Backtrace: =========
/lib/libc.so.6(+0x78e66)[0x7f2869f19e66]
dhcpcd[0x40cdd0]
dhcpcd[0x40e597]
dhcpcd[0x4093f0]
dhcpcd[0x40aa8a]
dhcpcd[0x4028a8]
/lib/libc.so.6(__libc_start_main+0xed)[0x7f2869ec238d]
dhcpcd[0x402d1d]
======= Memory map: ========
00400000-00419000 r-xp 00000000 08:03 5767251 /sbin/dhcpcd
00619000-0061a000 r--p 00019000 08:03 5767251 /sbin/dhcpcd
0061a000-0061b000 rw-p 0001a000 08:03 5767251 /sbin/dhcpcd
0061b000-0061c000 rw-p 00000000 00:00 0
02055000-02077000 rw-p 00000000 00:00 0 [heap]
7f2869a6f000-7f2869a84000 r-xp 00000000 08:03 8393297 /usr/lib/libgcc_s.so.1
7f2869a84000-7f2869c84000 ---p 00015000 08:03 8393297 /usr/lib/libgcc_s.so.1
7f2869c84000-7f2869c85000 rw-p 00015000 08:03 8393297 /usr/lib/libgcc_s.so.1
7f2869c85000-7f2869c9c000 r-xp 00000000 08:03 5111814 /lib/libpthread-2.15.so
7f2869c9c000-7f2869e9b000 ---p 00017000 08:03 5111814 /lib/libpthread-2.15.so
7f2869e9b000-7f2869e9c000 r--p 00016000 08:03 5111814 /lib/libpthread-2.15.so
7f2869e9c000-7f2869e9d000 rw-p 00017000 08:03 5111814 /lib/libpthread-2.15.so
7f2869e9d000-7f2869ea1000 rw-p 00000000 00:00 0
7f2869ea1000-7f286a038000 r-xp 00000000 08:03 5111831 /lib/libc-2.15.so
7f286a038000-7f286a238000 ---p 00197000 08:03 5111831 /lib/libc-2.15.so
7f286a238000-7f286a23c000 r--p 00197000 08:03 5111831 /lib/libc-2.15.so
7f286a23c000-7f286a23e000 rw-p 0019b000 08:03 5111831 /lib/libc-2.15.so
7f286a23e000-7f286a242000 rw-p 00000000 00:00 0
7f286a242000-7f286a249000 r-xp 00000000 08:03 5111816 /lib/librt-2.15.so
7f286a249000-7f286a448000 ---p 00007000 08:03 5111816 /lib/librt-2.15.so
7f286a448000-7f286a449000 r--p 00006000 08:03 5111816 /lib/librt-2.15.so
7f286a449000-7f286a44a000 rw-p 00007000 08:03 5111816 /lib/librt-2.15.so
7f286a44a000-7f286a46b000 r-xp 00000000 08:03 5111845 /lib/ld-2.15.so
7f286a64c000-7f286a650000 rw-p 00000000 00:00 0
7f286a668000-7f286a66a000 rw-p 00000000 00:00 0
7f286a66a000-7f286a66b000 r--p 00020000 08:03 5111845 /lib/ld-2.15.so
7f286a66b000-7f286a66c000 rw-p 00021000 08:03 5111845 /lib/ld-2.15.so
7f286a66c000-7f286a66d000 rw-p 00000000 00:00 0
7fff6c17d000-7fff6c19e000 rw-p 00000000 00:00 0 [stack]
7fff6c1ff000-7fff6c200000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]

Additional info:
dhcpcd 5.5.5
Copyright (c) 2006-2012 Roy Marples

# A sample configuration for dhcpcd.
# See dhcpcd.conf(5) for details.

# Inform the DHCP server of our hostname for DDNS.
hostname
# To share the DHCP lease across OSX and Windows a ClientID is needed.
# Enabling this may get a different lease than the kernel DHCP client.
# Some upstream DHCP servers may also require a ClientID, such as FRITZ!Box.
#clientid

# A list of options to request from the DHCP server.
option domain_name_servers, domain_name, domain_search, host_name
option classless_static_routes
# Most distributions have NTP support.
option ntp_servers
# Respect the network MTU.
option interface_mtu
# A ServerID is required by RFC2131.
require dhcp_server_identifier

# A hook script is provided to lookup the hostname if not set by the DHCP
# server, but it should not be run by default.
nohook lookup-hostname
noipv4ll

Steps to reproduce:
No idea.