I've gone as far as I am going with this. The allocation failure happens in _int_malloc, but that is a 530 line abomination. Stepping through that with "stepi" is ridiculous. MALLOC_CHECK_ did not add any info. valgrind merely reported that there were no allocations.
$ /lib64/libc.so.6 GNU C Library stable release version 2.11.2 (20100531), by Roland McGrath et al. Copyright (C) 2009 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Configured for x86_64-suse-linux. Compiled by GNU CC version 4.5.0 20100604 [gcc-4_5-branch revision 160292]. Compiled on a Linux 2.6.32 system on 2010-07-19. Available extensions: crypt add-on version 2.1 by Michael Glad and others GNU Libidn by Simon Josefsson Native POSIX Threads Library by Ulrich Drepper et al BIND-8.2.3-T5B For bug reporting instructions, please see: <http://www.gnu.org/software/libc/bugs.html>.