Re: propolice support for linux

[Han Boetes <han@mijncomputer.nl>]

Ulrich Drepper wrote:
> Aside from all the arguments about why this patch isn't good for
> the kernel, everybody should be aware that the ProPolice gcc
> patches are pretty unusable. They rely in recognizing certain
> tree patterns which for some architectures do not exist, and for
> others can look differently, depending on the optimization. To
> paraphrase one of the gcc developers: "this kind of
> functionality should be written to work _with_ gcc, not
> _against_ it as the propolice patch does".
>
> Before you suggest using something like this patch you better
> first inform yourself by asking the people who actually know the
> code which is modified.

Ok I have a problem here. You are Ulrich Drepper and you are _the_
maintainer of glibc and I am Han Boetes and I am a C noob. It's
like Kasparov trying to explain something to a club-chess-player.

I'm afraid that whatever explanation you give to me is over my
head, you'll feel like talking to a dummy and I'll be terribly
unsatisfied.

To avoid that I would like to ask you if you can show me some
example-code, something I which can compile and run and see for
myself, for the following situations:

1) Where an application compiled with PP is working worse or even
   failing where it would work right without PP.

2) Where a bufferoverflow can be exploited even though the
   application is compiled with PP.


As an example where PP does work right the test-code provided by
the propolice maintainer:

    /* test-propolice.c */
    #define OVERFLOW "This is longer than 10 bytes"
    #include <string.h>
    int main (int argc, char *argv[]) {
        char buffer[10];
        strcpy(buffer, OVERFLOW);
        return 0;
    }




# Han