[mp1] PerlFreshRestart, perl_reload_inc, segmentation fault (patch)

[Michael Rendell <mi...@cs.mun.ca>]

Subject: [mp1] PerlFreshRestart, perl_reload_inc, segmentation fault (patch)

When using mod_perl-1.30 (with perl 5.8.5, apache 1.3.37)
with "PerlFreshRestart On" (yes, dangerous), httpd gets a segmentation
fault.  Using valgrind, discovered that part of the problem is related
to the way memory is used in perl_reload_inc() (src/modules/perl/perl_util.c):

            void perl_reload_inc(server_rec *s, pool *sp)
            ...
     1      hv_iterinit(hash);
     2      while ((entry = hv_iternext(hash))) {
     3*         ap_table_setn(reload, HeKEY(entry), "1");
     4      }
     5
     6      {
     7          array_header *arr = ap_table_elts(reload);
     8          table_entry *elts = (table_entry *)arr->elts;
     9          SV *keysv = newSV(0);
    10          for (i=0; i < arr->nelts; i++) {
    11              sv_setpv(keysv, elts[i].key);
    12              if (!(entry = hv_fetch_ent(hash, keysv, FALSE, 0))) {
    13                  MP_TRACE_g(fprintf(stderr,
    14                                     "%s not found in %%INC\n", 
elts[i].ke
y));
    15                  continue;
    16              }
    17*             hv_delete_ent(hash, keysv, G_DISCARD, 0);
    18              MP_TRACE_g(fprintf(stderr, "reloading %s\n", 
elts[i].key));
    19*             perl_require_pv(elts[i].key);
    20          }
    21          SvREFCNT_dec(keysv);
    22      }

at line 3, ap_table_setn() does make take a copy of the string (it uses the
memory that is in the perl hash); at line 17, the hash entry is deleted
(memory free'd), and at line 19, the value is used.

Changing the ap_table_setn() to ap_table_set() fixes this particular
problem.

Hope this is useful,
Michael

Re: [mp1] PerlFreshRestart, perl_reload_inc, segmentation fault (patch)

["Philippe M. Chiasson" <go...@ectoplasm.org>]

Michael Rendell wrote:
> Subject: [mp1] PerlFreshRestart, perl_reload_inc, segmentation fault (patch)
> 
> When using mod_perl-1.30 (with perl 5.8.5, apache 1.3.37)
> with "PerlFreshRestart On" (yes, dangerous), httpd gets a segmentation
> fault. 

Yup, verified this one.

> Using valgrind, discovered that part of the problem is related
> to the way memory is used in perl_reload_inc() (src/modules/perl/perl_util.c):
> 
> [...]
> 
> Changing the ap_table_setn() to ap_table_set() fixes this particular
> problem.
> 
> Hope this is useful,

Very much so! Thanks a lot.

Committed revision 600439.

-- 
Philippe M. Chiasson     GPG: F9BFE0C2480E7680 1AE53631CB32A107 88C3A5A5
http://gozer.ectoplasm.org/       m/gozer\@(apache|cpan|ectoplasm)\.org/