Re: [Qemu-devel] qemu_malloc failing

[Mulyadi Santosa]

Hi...

On Sun, Apr 10, 2011 at 09:08, Brad Hards <address@hidden> wrote:
> Program received signal SIGSEGV, Segmentation fault.
> 0x00007ffff5a4e66c in malloc_consolidate (av=0x7ffff5d55e40) at malloc.c:5161
> 5161    malloc.c: No such file or directory.
>        in malloc.c
> (gdb) bt
> #0  0x00007ffff5a4e66c in malloc_consolidate (av=0x7ffff5d55e40) at 
> malloc.c:5161
> #1  0x00007ffff5a51e82 in _int_malloc (av=0x7ffff5d55e40, bytes=2128) at 
> malloc.c:4373
> #2  0x00007ffff5a5338e in __libc_malloc (bytes=2128) at malloc.c:3660
> #3  0x000000000042b3d6 in qemu_malloc (size=2128) at qemu-malloc.c:49
> #4  0x000000000056100f in uhci_async_alloc (s=0x15dcc10) at 
> /home/bradh/qemu-codingstyle.git/hw/usb-uhci.c:167

looking at:
http://www.linuxquestions.org/questions/programming-9/segfault-in-malloc_consolidate-363048/

and

http://www.linuxquestions.org/questions/linux-general-1/malloc_consolidate-757663/

I feel that it's somekind double free or data overwriting the malloc
metadata.... thus causing trouble during memory block coalescing...

First thing I suggest is to check if malloc() is always followed by
proper free().... and then see how much we really fill data into that
allocated block (think about malloc exploit explained in Phrack...)

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com