Re: [Valgrind-users] Empty pointers to source code

[Nicholas N. <nj...@ca...>]

On Fri, 9 Apr 2004, G B wrote:

>  --- Nicholas Nethercote <nj...@ca...> wrote:
> > > Is this valgrind finding a bug in
> > > a) itself?
> > > b) libc?
> > > c) my program?
> >
> > Maybe b, maybe c.  A longer stack trace (eg.
> > --num-callers=20) will
> > hopefully make it clearer.
>
> ==2872== Invalid free() / delete / delete[]
> ==2872==    at 0x7501CDEC: free (in
> /usr/lib/valgrind/vgpreload_addrcheck.so)
> ==2872==    by 0x7540B9B3: (within /lib/libc-2.3.3.so)
> ==2872==    by 0x7540B6F9: __libc_freeres (in
> /lib/libc-2.3.3.so)
> ==2872==    by 0x75018BBE: (within
> /usr/lib/valgrind/vg_inject.so)
> ==2872==    by 0x7533104A: exit (in
> /lib/libc-2.3.3.so)
> ==2872==    by 0x75106C19: processEventsAndTimeouts
> (in /usr/lib/libglut.so.3.7.1)
> ==2872==    by 0x8F: ???
> ==2872==  Address 0x759D0818 is not stack'd, malloc'd
> or free'd
>
> The above was obtained with --num-callers=20. Any
> ideas what could be lurking at 0x8F?

Stack-walking is not always reliable, I think Valgrind's getting confused
here, and wouldn't pay too much attention to the 0x8f.  Try with
--run-libc-freeres=no.  If you don't get an error, then I think it shows
that the problem is with glibc -- libc-freeres is a glibc routine that
frees up all glibc's memory.

N