c++ weird error message

Question

Someone has reported a bug in my program, which brings up the following error message:

The error occours in a C++ DLL of the program, which was compiled by VS2008. I can reproduce the error, but am not able to find out what´s the problem. I´ve already done a bunch of tests for memory leaks or wrong alloctions, but with no success.

Now the weird thing: when I add a main function to the code, compile it as an EXE and then run the exactly same thing, all is ok. The error occours only as a DLL. The next strange thing is, that when I press "Ignore", the program continues and does its job as expected.

So, I´m looking for 2 types of answers: - Answers that help me find the bug - Answers that help me to "auto-ignore" or hide this errormessage, so that it does not occour. That would be ok, since there is no difference in the result.

I´m thankful for any help or advise.

Thanks!

Update

Like Joachim Pileborg said, I´ve created a simple test c++ project, that calls my DLL, and it works perfectly! The program that normally calls the DLL is written in DELPHI, so I think it could be a bug of DELPHI... Weird: The call of the DLL works for 99.9999..%, but in one specific case, there occours an error IN the Dll. It´s not the call that fails... Really, really strange story :S

Answer 1

Through the debugger, I was able to see the call stack, and what function in the code displayed the error. After searching for this routine, I could find out how to disable displaying it.

Answer 2

4294967292 - that is (unsigned)-4. You are either doing some computation of the size to be allocated wrong, some integer has overflown or somesuch.

I'd try to put a breakpoint on malloc (or whatever allocation function that is) and check where does the bad value come from.

Answer 3

Ok... that is a negative number. The simpler thing... perhaps your code is doing a malloc with an invalid\negative size?

The strange thing is that that number in binary is 11111111111111111111111111111100, probably your size calculation is wrong. It can be however a more complicated error, for example due a buffer overflow.

You should not ignore this error at all, can be a symptom of a more complicated and dangerous error. Try to debug your allocation, try to get exactly the piece of code that is doing this invalid allocation.

You can overload the new operator or redefine the malloc replacing them your debug functions where you can check the passed arguments (size).