Re: [Bug-glpk] [Fwd: segfault reading a compressed mps file in 4.52]

[Andrew Makhorin]

Thank you for your bug report.

> 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).

Most of GNU mailing lists require subscription because of a lot of spam.

> 
> 
> 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)

Glpsol 4.52 correctly reads your version of greenbea.gz on my 32-bit
Linux machine:

address@hidden:~/Desktop/glpk-4.52/examples$ ./glpsol greenbea.gz
GLPSOL: GLPK LP/MIP Solver, v4.52
Parameter(s) specified in the command line:
 greenbea.gz
Reading problem data from `greenbea.gz'...
Problem: GREENBEA
Objective: FAT0..J.
2393 rows, 5405 columns, 31499 non-zeros
19226 records were read

Your test program also works correctly:

address@hidden:~/Desktop/glpk-4.52/examples$ gcc -I../src
bug.c ../src/.libs/libglpk.a -lm
address@hidden:~/Desktop/glpk-4.52/examples$ ./a.out
Reading problem data from `greenbea.gz'...
Problem: GREENBEA
Objective: FAT0..J.
2393 rows, 5405 columns, 31499 non-zeros
19226 records were read

So I think there is something wrong with building of glpk. How did you
build it (i.e. which flags did you specify for configure and make)? And
how did you compile your test program? Please note that glpk has its own
version of zlib, which is included in libglpk.

> 
> As an additional (even though probably irrelevant) detail, I'll add
> that the file type flag (GLP_MPS_DECK vs GLP_MPS_FILE) does not make
> any difference.
> 

GLP_MPS_DECK is a fixed-column format, and if no field names are
omitted, it is a subset of GLP_MPS_FILE which is a free format. Please
see the glpk reference manual for difference between these two formats.


Andrew Makhorin