Re: [Valgrind-users] vgPlain___libc_freeres_wrapper: Address 0x4049B5C0 is not stack'd, malloc'd or free'd

[Simon J. <ja...@ex...>]

Nicholas Nethercote <nj...@ca...> writes:

> On Mon, 1 Dec 2003, Simon Josefsson wrote:
>
>> Yes, I read FAQ #1, but I'm using the latest glibc (which glibc
>> versions are considered too old/buggy in FAQ #1, btw?).  But why
>> doesn't the problem occur when I link with other libraries?  The glibc
>> is the same.  I have been using valgrind extensively on other projects
>> on this machine, so it must be some interaction between this
>> particular library, valgrind and possibly the system.  All libraries
>> are built on the same machine, with the same compiler etc.
>
> I guess that libshishi allocates some memory upon startup (in its .init
> section, even if it's not used at all), and then something goes wrong
> later when it tries to deallocate it... which seems to be triggered by
> __libc_freeres.  I don't know anything beyond that.

Thanks for the ideas, libshishi.so do define a '_init' symbol, but I
didn't write it.  So it probably is the default so initializer.
Linking with all of the other libraries that libshishi depend on
doesn't cause the same problem, so the problem probably isn't a _init
from one of the other libraries either.  Weird.  I'll see if I can
remove things from libshishi until the problem disappears.

jas@latte:~$ gcc -g -o foo foo.c -lshishi
jas@latte:~$ gdb ./foo
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This GDB was configured as "i386-linux"...
(gdb) b _init
Breakpoint 1 at 0x804836a
(gdb) r
Starting program: /home/jas/foo
 
Breakpoint 1, 0x0804836a in _init ()
(gdb) disass
Dump of assembler code for function _init:
0x8048364 <_init>:      push   %ebp
0x8048365 <_init+1>:    mov    %esp,%ebp
0x8048367 <_init+3>:    sub    $0x8,%esp
0x804836a <_init+6>:    call   0x80483d4 <call_gmon_start>
0x804836f <_init+11>:   call   0x8048440 <frame_dummy>
0x8048374 <_init+16>:   call   0x8048560 <__do_global_ctors_aux>
0x8048379 <_init+21>:   leave
0x804837a <_init+22>:   ret
End of assembler dump.
(gdb) s
Single stepping until exit from function _init,
which has no line number information.
0x080484bb in __libc_csu_init ()
(gdb) disass
Dump of assembler code for function __libc_csu_init:
0x80484a0 <__libc_csu_init>:    push   %ebp
0x80484a1 <__libc_csu_init+1>:  mov    %esp,%ebp
0x80484a3 <__libc_csu_init+3>:  push   %edi
0x80484a4 <__libc_csu_init+4>:  push   %esi
...