Re: stackguard-like embedded protection

[antirez <antirez () linuxcare com>]

On Mon, Sep 11, 2000 at 11:34:01AM +0900, Hiroaki Etoh wrote:
> I don't think this solution is portable to any C compiler.  Because the ordering
> of local variables is very dependent of the implementation of compilers, for
> example, Visual C++ by Microsoft.  I don't know the current version of GCC
> compiler preserves the ordering of local variables. Therefore, I implemented
> ProPolice at the intermediate language level.

I tested GCC i386 and sparc with a lot of optimizations and options:
it seems that if the variable is declared with the specifier 'volatile'
always goes next to the RET. I have no access to other compilers,
but since implementing ProPolice at the intermediate language level
you needs to implement it for all the compilers it seems that my
solution can be more portable in some case. For example it can work
in new compilers without changes, ProPolice can't.
Also ProPolice needs to be implemented in a different way for different
compilers: you can add #ifdefs to my header file to make it compatible
with strange-behaviour compilers.

regards,
antirez

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Salvatore Sanfilippo, Open Source Developer, Linuxcare Italia spa
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