Re: [Valgrind-users] Finding illegal memory accesses when Valgrind fails via an assertion

[Ashley P. <as...@qu...>]

Stephen Torri wrote:
>> My (buggy) program dies like this:
>> % valgrind: vg_malloc2.c:442 (bszW_to_pszW): Assertion 'pszW >= 0' failed.
>>
>> If Memcheck (the memory checker) shows any invalid reads, invalid
>> writes and invalid frees in your program, the above may happen. Reason
>> is that your program may trash Valgrind's low-level memory manager,
>> which then dies with the above assertion, or something like this. The
>> cure is to fix your program so that it doesn't do any illegal memory
>> accesses. The above failure will hopefully go away after that.
> 
> The above is a quotation from the Valgrind FAQ. Without sounding
> sarcastic the answer is not that helpful. The point that I am using
> Valgrind is to find the illegal memory accesses. I started my program
> with the following flags when I got a similar assertion:
> 
> valgrind -v --tool=memcheck --leak-resolution=high ./reverse --file
> kernel32.dll 
> 
> What flags should I be using or is there another tool in valgrind I
> should be using instead of memcheck? I do not have a strong skill using
> Valgrind to find errors. So any help would be appreciated.

I think as Olly said the Valgrind FAQ entry is only relevant if you
*haven't* had any previous errors reported.

My understanding is the error reported is your application did a invalid
write to somewhere which corrupted some valgrind metadata which in time
caused it to crash.  You should proceed by fixing the error reported
first and then re-run the application, the likelyhood is that valgrind
will no longer crash.

Ashley,