right list for SIGABRT python binary question ?

[Karsten Hilbert]

On Wed, Nov 01, 2017 at 09:21:46AM +0100, dieter wrote:

> >> It points to a memory corruption.
> 
> The i386/x64 architecture supports memory access breakpoints
> and GDB, too, has support for this. You know the address which
> gets corrupted. Thus, the following apporach could have a chance
> to succeed:
> 
>    Put a "memory write" breakpoint on the address which gets corrupted.
>    this should stop the program each time this address is written;
>    Check then the backtrace. As the address forms part of the
>    address block prologue, it should only be accessed from
>    Python's "malloc" (and "free") implementation. Any other access
>    indicates bad behaviour.

I understand. Thank you for the explanation. This may seem
like a dumb question: the actual address that gets corrupted
varies from run to run (it may be the same "place" in the
code but that place gets put at a different address each
run). Since I don't know the address of a given run, how do I
set a break point on that address ?  It seems to me I first
need to map the "place" to its address before the SIGABRT
happens. How do I find out out which "place" needs to be
mapped from the output I already have ?

(the "place" is the memory block you refer to)

Other than that I understand what you are getting at and am
willing to try.

Thanks,
Karsten

>    Should your program get stopped too often (because the memory
>    block is reused too often), you must find a good point in your
>    program to activate the memory access breakpoint in a delayed way.
>    You could use the Python debugger for this: execute significant
>    parts of your program in the Python debugger; switching to
>    GDB, check whether the address is already corrupted - if
>    so, restart and refine the checks above in the portion of your program
>    which caused the corruption. If the part in your program
>    is sufficiently small, you can activate the memory access breakpoint.
>    This approach may also be feasible, should you use a CPU
>    without memory access breakpoints.


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