Re: Hi, Needs suggestions for finding and fixing stack/memory corruption when calling a function

Hi Glynn,


On Tue, May 24, 2011 at 1:48 PM, Glynn Clements
<[email protected]> wrote:
>
> Fawad Lateef wrote:
>
>> For now I added two more temporary arguments between 1st and 2nd
>> arguments and the required arguments getting correct values thats
>> why I am assuming that by adding temporary variables we moved the
>> memory corruption from real arguments into temporary arguments.
>> After adding these arguments my function is behaving correctly so
>> for now this is a work-around _but_ I want to figure-out its proper
>> fix (as the same sort of issue we faced in our cgi based web-pages
>> code some weeks earlier).
>>
>> Hence I needs suggestion that is this really a memory corruption or
>> some compiler issues ? If its a compiler issue then its not a big
>> problem but if its memory corruption issue then we have to _fix_ it
>> asap.
>
> Check the assembler output ("gcc -S ...").
>

Nice idea, will look into this.

> Personally, I'd be more inclined to suspect register corruption. Are
> you calling a library function which use a different ABI? E.g. if your
> code is compiled for an ABI where certain registers are preserved but
> calling a function using an ABI which doesn't preserver those
> registers, then you'll have problems.
>

humm, Can you give some suggestion about how to verify this ? Using
readelf or objdump on different libraries and executables can give
some clue ? As we are using some pre-compiled  libraries provided by
some stack we are using.

Thanks for the help.

Regards,

Fawad Lateef


> --
> Glynn Clements <[email protected]>
>