After setting up access to a new wireless network, I've found the dhcpcd crashes regularly with messages similar to the following:

*** glibc detected *** dhcpcd: double free or corruption (fasttop): 0x0000000000c85860 ***
======= Backtrace: =========
/lib/libc.so.6(+0x78a56)[0x7f02fb0d6a56]
dhcpcd[0x40cdd0]
dhcpcd[0x40e597]
dhcpcd[0x4093f0]
dhcpcd[0x411ba7]
dhcpcd[0x411563]
dhcpcd[0x40768f]
dhcpcd[0x40aa6b]
dhcpcd[0x4028a8]
/lib/libc.so.6(__libc_start_main+0xf5)[0x7f02fb07f455]
dhcpcd[0x402d1d]
======= Memory map: ========
00400000-00419000 r-xp 00000000 fe:01 787833 /sbin/dhcpcd
00619000-0061a000 r--p 00019000 fe:01 787833 /sbin/dhcpcd
0061a000-0061b000 rw-p 0001a000 fe:01 787833 /sbin/dhcpcd
0061b000-0061c000 rw-p 00000000 00:00 0
00c84000-00ca6000 rw-p 00000000 00:00 0 [heap]
7f02fac2d000-7f02fac42000 r-xp 00000000 fe:01 1059988 /usr/lib/libgcc_s.so.1
7f02fac42000-7f02fae41000 ---p 00015000 fe:01 1059988 /usr/lib/libgcc_s.so.1
7f02fae41000-7f02fae42000 rw-p 00014000 fe:01 1059988 /usr/lib/libgcc_s.so.1
7f02fae42000-7f02fae59000 r-xp 00000000 fe:01 393392 /lib/libpthread-2.15.so
7f02fae59000-7f02fb058000 ---p 00017000 fe:01 393392 /lib/libpthread-2.15.so
7f02fb058000-7f02fb059000 r--p 00016000 fe:01 393392 /lib/libpthread-2.15.so
7f02fb059000-7f02fb05a000 rw-p 00017000 fe:01 393392 /lib/libpthread-2.15.so
7f02fb05a000-7f02fb05e000 rw-p 00000000 00:00 0
7f02fb05e000-7f02fb1f5000 r-xp 00000000 fe:01 394177 /lib/libc-2.15.so
7f02fb1f5000-7f02fb3f5000 ---p 00197000 fe:01 394177 /lib/libc-2.15.so
7f02fb3f5000-7f02fb3f9000 r--p 00197000 fe:01 394177 /lib/libc-2.15.so
7f02fb3f9000-7f02fb3fb000 rw-p 0019b000 fe:01 394177 /lib/libc-2.15.so
7f02fb3fb000-7f02fb3ff000 rw-p 00000000 00:00 0
7f02fb3ff000-7f02fb406000 r-xp 00000000 fe:01 393518 /lib/librt-2.15.so
7f02fb406000-7f02fb605000 ---p 00007000 fe:01 393518 /lib/librt-2.15.so
7f02fb605000-7f02fb606000 r--p 00006000 fe:01 393518 /lib/librt-2.15.so
7f02fb606000-7f02fb607000 rw-p 00007000 fe:01 393518 /lib/librt-2.15.so
7f02fb607000-7f02fb628000 r-xp 00000000 fe:01 397247 /lib/ld-2.15.so
7f02fb7ff000-7f02fb803000 rw-p 00000000 00:00 0
7f02fb826000-7f02fb828000 rw-p 00000000 00:00 0
7f02fb828000-7f02fb829000 r--p 00021000 fe:01 397247 /lib/ld-2.15.so
7f02fb829000-7f02fb82a000 rw-p 00022000 fe:01 397247 /lib/ld-2.15.so
7f02fb82a000-7f02fb82b000 rw-p 00000000 00:00 0
7fff4631f000-7fff46340000 rw-p 00000000 00:00 0 [stack]
7fff463ff000-7fff46400000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
Aborted

I couldn't say whether this is something specific to this network (WPA-EAP) or if it was triggered by a package upgrade around the same time. Although, dhcpcd doesn't seem to crash for me on my home network (WPA2-PSK).

[kmshanah@nakor ~]$ pacman -Q glibc dhcpcd wpa_supplicant linux
glibc 2.15-10
dhcpcd 5.5.5-1
wpa_supplicant 0.7.3-5
linux 3.2.13-1