Re: New dynamic loader (was Re: 2.1.96 & apache mod_setenv)

[Petr Vandrovec]

On 10 Nov 00 at 9:48, Ulrich Drepper wrote:
> 
> > Then look at my last mail. Simple
> > 
> > dlopen(".../php_auth_vsbtuo.so", RTLD_NOW);
> > dlopen(".../libldap.so", RTLD_NOW);
> 
> I don't have this and won't install it.  Go to the Debian guys and let
> them figure this out.

Hi Ulrich,
  that's me again. It looks like that symbol lists are somewhat
damaged during loading/unloading of previous .so modules:

15603:  
15603:  relocation processing: /lib/libpam.so.0
15603:  symbol=__ctype_tolower;  lookup in file=./x
15603:  symbol=__ctype_tolower;  lookup in file=/usr/lib/debug/libdl.so.2
15603:  symbol=__ctype_tolower;  lookup in file=/usr/lib/debug/libc.so.6
15603:  binding file /lib/libpam.so.0 to /usr/lib/debug/libc.so.6: normal 
symbol `__ctype_tolower' [GLIBC_2.0]
15603:  symbol=_pam_token_returns;  lookup in file=./x
15603:  symbol=_pam_token_returns;  lookup in file=/usr/lib/debug/libdl.so.2
15603:  symbol=_pam_token_returns;  lookup in file=/usr/lib/debug/libc.so.6
15603:  symbol=_pam_token_returns;  lookup in file=/usr/lib/debug/ld-2.1.97.so

and now it dies in elf/do-lookup.h at line 52:

map = list[i];

because of list was NULL. 

_dl_lookup_symbol was invoked with symbol_scope[] containing 
{0x2aac0860, 0x2aac1588, 0}. 0x2aac0860 points to health structure 
{r_list=0x2aac0dd4, r_nlist=4, r_duplist=0x2aac0de4, r_nduplist=5 }. 
But 0x2aac1588 points to 
{r_list=NULL, r_nlist=0, r_duplist=NULL, r_nduplist=0}.

Is it just bug that elf/do-lookup.h:FCT uses do {} while() instead
of while () {}, so it dereferences pointer even for zero length list,
or is it something worse and such item should not appear in
symbol_scope array at all? 

I'm now trying to recompile glibc with while() {} instead of 
do {} while() loop, but it will take some time on my hardware :-(
                                       Thanks,
                                              Petr Vandrovec
                                              address@hidden