[Wien] crash in tetra -enefile

[Pavel Ondračka]

Dear Wien2k mailing list,
there is a small bug in tetra -enefile which could occasionally result
in a crash like this:

x tetra -enefile
Program received signal SIGSEGV: Segmentation fault - invalid memory
reference.
Backtrace for this error:
Segmentation fault (core dumped)
0.023u 0.389s 0:00.56 71.4%	0+0k 0+216io 0pf+0w

This is an uninitialized variable problem (here reproducible with
gfortran 8.2.1 and with the right star alignment due to the dependence
on random uninitialized memory) 

The crash happens at tetra.f:464
tetra.f:462   if(nnsum_dos.gt.0) then
tetra.f:463         do i=1,nnsum_dos
tetra.f:464           WRITE(6,1176)
i,(isumdos(i,i1),i1=1,nnsum_dos_max)
with out of bound read of isumdos, (I don't have any SUM in my int
file) hence the "if(nnsum_dos.gt.0)" should be false, but nnsum_dos is
unitialized at this point.

valgrind:
==30563== Conditional jump or move depends on uninitialised value(s)
==30563==    at 0x40A38E: MAIN__ (tetra.f:462)
==30563==    by 0x40B3B3: main (tetra.f:6)
(gdb) print nnsum_dos
$1 = 528

The variable is supposed to be set here:
tetra.f:256      nnsum_dos=0
tetra.f:257      read(5,'(a)',end=91) system
tetra.f:258      if(system(1:3).ne.'SUM') goto 91
tetra.f:259      read(system(5:70),*,ERR=91,END=91)
nnsum_dos,nnsum_dos_max

however the entire block is skipped with -enefile due to 
tetra.f:216       if(enefile) goto 200
which jumps to
tetra.f:343  200  CONTINUE

The solution is to zero-initialize the nnsum_dos variable earlier
(before the goto 200 jump or at the file beginning).

While the crash looks scary, it is likely harmless since it crashes
almost at the end where all important data should be written anyway,
reporting nevertheless. 

Best regards
Pavel