Help with debug

[Phil Lodwick]

Hi,

I have been debugging a problem today and am running low on batteries.  I am
hoping somebody can look at the attached snippet of log and point me in the
right direction.

>From what I can tell, there is a DLL called snoopy.dll that does a whole
bunch of allocs and reallocs and then tries to reference a NULL pointer which
causes an unhandled exception.  The code goes through a loop and does not
always crash on the same iteration, but it always seems to crash at the same
address.

This code does not crash on Windows.  Just getting lucky?

Unfortunately I do not have the sources to this code, so it makes life a
little more difficult.  

Any good ideas for my next step in debugging?

Thanks,
Phil
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000e:Call ntdll.RtlAllocateHeap(41210000,00000000,00000030) ret=7c3416b3
000e:trace:heap:RtlAllocateHeap (0x41210000,00000002,00000030): returning 0x46927938
000e:Ret  ntdll.RtlAllocateHeap() retval=46927938 ret=7c3416b3
000e:Call ntdll.RtlReAllocateHeap(41210000,00000000,4692a240,00000238) ret=7c3527e9
000e:trace:heap:RtlReAllocateHeap (0x41210000,00000002,0x4692a240,00000238): returning 0x46927970
000e:Ret  ntdll.RtlReAllocateHeap() retval=46927970 ret=7c3527e9
000e:trace:seh:__regs_RtlRaiseException code=c0000005 flags=0 addr=0x1133572a
000e:trace:seh:__regs_RtlRaiseException  info[0]=00000000
000e:trace:seh:__regs_RtlRaiseException  info[1]=00000000
000e:trace:seh:__regs_RtlRaiseException  eax=00000001 ebx=00000000 ecx=00000000 edx=00000000 esi=456b68b8 edi=46929d50
000e:trace:seh:__regs_RtlRaiseException  ebp=456b6880 esp=456b6598 cs=0073 ds=007b es=007b fs=003b gs=0033 flags=00010246
000e:Call ntdll.RtlEnterCriticalSection(4148f460) ret=41440765
000e:Ret  ntdll.RtlEnterCriticalSection() retval=00000000 ret=41440765
000e:Call ntdll.RtlLeaveCriticalSection(4148f460) ret=414407a6
000e:Ret  ntdll.RtlLeaveCriticalSection() retval=00000000 ret=414407a6
000e:trace:seh:EXC_CallHandler calling handler at 0x113f6cae code=c0000005 flags=0

...

Unhandled exception: page fault on read access to 0x00000000 in 32-bit code (0x1133572a).


Backtrace:
=>1 0x1133572a in snoopy (+0x18572a) (0x456b6880)
  2 0x11337e52 in snoopy (+0x187e52) (0x00000000)

0x1133572a: movl   0x0(%ebx),%ecx

Modules:
Module	Address			Debug info	Name (140 modules)
PE	0x111b0000-1149b000	Export          snoopy 

Threads:
process  tid      prio (all id:s are in hex)
	00000016    0
	00000015    0
	00000014    0
	00000012    0
	00000010    0
	0000000f    0
	0000000e    0 <==
	0000000d    0
	0000000c    0
	0000000b    0
	0000000a    0
	00000009    0