[klee-dev] Klee & pointers

[Breger, Igor (Mobileye)]

Hi Cristian,
Thank you very much for the prompt reply.

Regards,
Igor

-----Original Message-----
From: klee-dev-bounces at imperial.ac.uk <klee-dev-bounces at imperial.ac.uk> On Behalf Of Cristian Cadar
Sent: Wednesday, August 12, 2020 17:19
To: klee-dev at imperial.ac.uk
Subject: Re: [klee-dev] Klee & pointers

Hi Igor,

For this example, I don't think it makes sense to make the pointer itself symbolic.  You could instead replace the klee_make_symbolic call with klee_make_symbolic(a, sizeof(*a), "a"); to make the malloc'ed memory symbolic.

If you're interested in symbolic pointers more generally, I would recommend this paper, which contains in the beginning a discussion of the different memory models used in symbolic execution (as well as proposing a new model):
https://srg.doc.ic.ac.uk/publications/19-segmem-esecfse.html

Best,
Cristian

On 09/08/2020 14:45, Breger, Igor (Mobileye) wrote:
> Hi all,
> 
> I am trying to generate function coverage tests.  From the tutorial 
> and mail-archive I could not understand how I can define  pointer as 
> symbolic and also the data it point to.
> 
> In the follow example, if I make a pointer symbolic, most of the tests 
> KLEE generate are invalid ( 6 of 7 ) . The only valid test is with 
> NULL values.
> 
> I would appreciate any help.
> 
> Best Regards,
> 
> Igor
> 
> #include "klee/klee.h"
> 
> #include <stdlib.h>
> 
> int get_sign(int *a) {
> 
>    if ( a == NULL)
> 
>      return 2;
> 
>    int x = *a;
> 
>    if (x == 0)
> 
>      return 0;
> 
>    if (x < 0)
> 
>      return -1;
> 
>    else
> 
>      return 1;
> 
> }
> 
> int main() {
> 
>    int *a = (int*)malloc(sizeof(int));
> 
>    klee_make_symbolic(&a, sizeof(a), "a");
> 
>    return get_sign(a);
> 
> }
> 
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