Hello and sorry for the misunderstanding with the bug-glpk list, I have now subscribed (but, as a suggestion for improvement, I'll add that it's not clear that subscription is required to submit bugs from reading the GLPK homepage at
http://www.gnu.org/software/glpk/#bug).
Thanks for looking into this; here is the trace from running the code through valgrind; I'm not sure if this suggests a bug in my zlib version:
==28394== Memcheck, a memory error detector
==28394== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==28394== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==28394== Command: glpktst
==28394==
Reading problem data from `greenbea.gz'...
==28394== Invalid read of size 8
==28394== at 0x4EE393C: zlib_crc32 (crc32.c:259)
==28394== by 0x4EEA819: zlib_inflate (inflate.c:1232)
==28394== by 0x4EE791F: gz_decomp (gzread.c:189)
==28394== by 0x4EE7AE5: gz_fetch (gzread.c:245)
==28394== by 0x4EE7CB7: zlib_gzread (gzread.c:339)
==28394== by 0x4EE7DD2: zlib_gzgetc (gzread.c:398)
==28394== by 0x4E61494: _glp_lib_xfgetc (glpenv07.c:580)
==28394== by 0x4E9F70E: read_char (glpmps.c:167)
==28394== by 0x4E9FCC2: indicator (glpmps.c:214)
==28394== by 0x4EA0170: glp_read_mps (glpmps.c:395)
==28394== by 0x400767: main (in /home/carlo/tmp/glpktst)
==28394== Address 0x6aeb39f4b68 is not stack'd, malloc'd or (recently) free'd
==28394==
==28394==
==28394== Process terminating with default action of signal 11 (SIGSEGV)
==28394== Access not within mapped region at address 0x6AEB39F4B68
==28394== at 0x4EE393C: zlib_crc32 (crc32.c:259)
==28394== by 0x4EEA819: zlib_inflate (inflate.c:1232)
==28394== by 0x4EE791F: gz_decomp (gzread.c:189)
==28394== by 0x4EE7AE5: gz_fetch (gzread.c:245)
==28394== by 0x4EE7CB7: zlib_gzread (gzread.c:339)
==28394== by 0x4EE7DD2: zlib_gzgetc (gzread.c:398)
==28394== by 0x4E61494: _glp_lib_xfgetc (glpenv07.c:580)
==28394== by 0x4E9F70E: read_char (glpmps.c:167)
==28394== by 0x4E9FCC2: indicator (glpmps.c:214)
==28394== by 0x4EA0170: glp_read_mps (glpmps.c:395)
==28394== by 0x400767: main (in /home/carlo/tmp/glpktst)
==28394== If you believe this happened as a result of a stack
==28394== overflow in your program's main thread (unlikely but
==28394== possible), you can try to increase the size of the
==28394== main thread stack using the --main-stacksize= flag.
==28394== The main thread stack size used in this run was 8388608.
==28394==
==28394== HEAP SUMMARY:
==28394== in use at exit: 73,880 bytes in 20 blocks
==28394== total heap usage: 24 allocs, 4 frees, 77,108 bytes allocated
==28394==
==28394== LEAK SUMMARY:
==28394== definitely lost: 0 bytes in 0 blocks
==28394== indirectly lost: 0 bytes in 0 blocks
==28394== possibly lost: 0 bytes in 0 blocks
==28394== still reachable: 73,880 bytes in 20 blocks
==28394== suppressed: 0 bytes in 0 blocks
==28394== Rerun with --leak-check=full to see details of leaked memory
==28394==
==28394== For counts of detected and suppressed errors, rerun with: -v
==28394== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 2 from 2)
Segmentation fault (core dumped)