Possible crash on invalid input

[lexxmark]

I'm porting GNU bison on windows and got an issue describing crash on some invalid input file.
lexxmark/winflexbison#64

I reproduced it and stack trace is following:
states_free ()
closure_free()
bitset_free (ruleset);
BITSET_FREE_ (bset); <<<< bset is NULL

Could you check if it also affect original bison code under linux?

[akimd]

Hi @lexxmark
First of all, I apologize for the poor delays: I don't get notifications when issues are created, and that's very painful...

If I understand correctly, you are reporting a crash with a pretty old version of Bison (2.5.*), is that right? It might well be true, but the current release is 3.7.3, and with that version:

$ /opt/local/bin/bison /Users/akim/Downloads/rpcalc___win_bison_2.5.23_crash.y
/Users/akim/Downloads/rpcalc___win_bison_2.5.23_crash.y:21.37-22.0: erreur: « " » manquant en fin de fichier
   21 |     | exp '\n'      { printf(%.10g\n", $1); }
      |                                     ^~~~~~~~~
/Users/akim/Downloads/rpcalc___win_bison_2.5.23_crash.y:21.21-86.0: erreur: « } » manquant en fin de fichier
   21 |     | exp '\n'      { printf(%.10g\n", $1); }
      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~

Note that the test suite (including the examples) are run with address sanitizer enabled, so it is very unlikely that such a bug would remain unnoticed.

And FWIW, none of 3.0.5, 3.1, 3.2.4, 3.3.2, 3.4.2, 3.5.4, 3.6.4, 3.7.2 crashed. Not even the old 2.7

$ /usr/bin/bison /Users/akim/Downloads/rpcalc___win_bison_2.5.23_crash.y
/Users/akim/Downloads/rpcalc___win_bison_2.5.23_crash.y:10.9-22: syntax error, unexpected identifier, expecting string

Finally, the source code reads:

/* Free bitset BSET.  */
void
bitset_free (bitset bset)
{
  if (bset)
    {
      BITSET_FREE_ (bset);
      free (bset);
    }
}

so I really doubt there is a problem here.

Are you really using something older? There is no support for old Bisons. The only supported version currently is 3.7.3.

Cheers!

[lexxmark]

Thank you for investigation,

If I understand correctly, you are reporting a crash with a pretty old version of Bison (2.5.*), is that right?

No it's winflexbison version 2.5.23 that has flex 2.6.4 and bison 3.7.1

I apologize it seems I use some outdated version of the bitset.c source code:

...
   Copyright (C) 2002-2006, 2009-2015, 2018-2019 Free Software Foundation, Inc.

   Contributed by Michael Hayes (m.hayes@elec.canterbury.ac.nz).
...
void
bitset_free (bitset bset)
{
  BITSET_FREE_ (bset);
  free (bset);
}

I will update gnu lib source code from the latest bison release next time I will upgrade winflexbison and this issue in my project should vanish.

Thank you again and sorry for bothering you,
Alex

[akimd]

Thank you again and sorry for bothering you

😄 No worries. Cheers!