Tool for detecting Array overflow

[vashwath@rediffmail.com]

Hi all,
Is there any free tool available for detecting array overflow? I found
one which detects overflow of dynamic arrays. But I need a tool(or a
special compiler) which detects static array overflows too.

Thanks

[Chris McDonald]

Re: Tool for detecting Array overflow

vashwath@rediff mail.com writes:
[color=blue]
>Hi all,
>Is there any free tool available for detecting array overflow? I found
>one which detects overflow of dynamic arrays. But I need a tool(or a
>special compiler) which detects static array overflows too.[/color]

<OT>
Any helpful answer you receive will probably be very compiler-specific.
If using gcc, your instance of it may support the -fbounds-check
command line option.
</OT>

--
Chris.

[slebetman@yahoo.com]

Re: Tool for detecting Array overflow

vashwath@rediff mail.com wrote:[color=blue]
> Hi all,
> Is there any free tool available for detecting array overflow? I found
> one which detects overflow of dynamic arrays. But I need a tool(or a
> special compiler) which detects static array overflows too.
>[/color]

Just do what your teachers always tell you to do. Check your bounds
before using the array.

[Bjørn Augestad]

Re: Tool for detecting Array overflow

vashwath@rediff mail.com wrote:[color=blue]
> Hi all,
> Is there any free tool available for detecting array overflow? I found
> one which detects overflow of dynamic arrays. But I need a tool(or a
> special compiler) which detects static array overflows too.
>
> Thanks
>[/color]

On linux you can use valgrind, http://valgrind.kde.org.
Bjørn

[vashwath@rediffmail.com]

Re: Tool for detecting Array overflow

> <OT>[color=blue]
> Any helpful answer you receive will probably be very compiler-specific.
> If using gcc, your instance of it may support the -fbounds-check
> command line option.
> </OT>
>[/color]
Thanks for replying Chris.

Yes, I am using gcc for compilation.
I used the options you suggested for the following program

#include <stdio.h>

int main()
{
int a[10];

int i;

for(i=0;i<10;i+ +)
a[i] = i;


for(i=0;i<10;i+ +)
printf("a[%d]= %d ",i,a[i]);

printf("\n");
printf("i=%d\n" ,i);

a[i] = 10;/*Array overflow???*/

}

I gave the following command
gcc -w -Wall -fbounds-check arrBound.c

But it did not detect the overflow.
Am i using the options correctly.

[Bjørn Augestad]

[OT] Re: Tool for detecting Array overflow

vashwath@rediff mail.com wrote:[color=blue][color=green]
>> <OT>
>> Any helpful answer you receive will probably be very compiler-specific.
>> If using gcc, your instance of it may support the -fbounds-check
>> command line option.
>> </OT>
>>[/color]
> Thanks for replying Chris.
>
> Yes, I am using gcc for compilation.
> I used the options you suggested for the following program
>
> #include <stdio.h>
>
> int main()
> {
> int a[10];
>
> int i;
>
> for(i=0;i<10;i+ +)
> a[i] = i;
>
>
> for(i=0;i<10;i+ +)
> printf("a[%d]= %d ",i,a[i]);
>
> printf("\n");
> printf("i=%d\n" ,i);
>
> a[i] = 10;/*Array overflow???*/
>
> }
>
> I gave the following command
> gcc -w -Wall -fbounds-check arrBound.c
>
> But it did not detect the overflow.
> Am i using the options correctly.
>[/color]


Check the gcc man page for details regarding -fbounds-check. I have gcc
4.0.2 prerelease 20050901 (SUSE 10), and my man page states that
-fbounds-check works for fortran and java only.

Bjørn

[slebetman@yahoo.com]

Re: Tool for detecting Array overflow

vashwath@rediff mail.com wrote:[color=blue][color=green]
> > <OT>
> > Any helpful answer you receive will probably be very compiler-specific.
> > If using gcc, your instance of it may support the -fbounds-check
> > command line option.
> > </OT>
> >[/color]
> Thanks for replying Chris.
>
> Yes, I am using gcc for compilation.
> I used the options you suggested for the following program
>
> #include <stdio.h>
>
> int main()
> {
> int a[10];
>
> int i;
>
> for(i=0;i<10;i+ +)
> a[i] = i;
>
>
> for(i=0;i<10;i+ +)
> printf("a[%d]= %d ",i,a[i]);
>
> printf("\n");
> printf("i=%d\n" ,i);
>
> a[i] = 10;/*Array overflow???*/
>
> }
>
> I gave the following command
> gcc -w -Wall -fbounds-check arrBound.c
>
> But it did not detect the overflow.
> Am i using the options correctly.[/color]

In your code, I never exceed 9. So it did not detect overflow because
there is no overflow. Just modify it with the following to cause
overflow:

int main()
{
int a[10];

int i;

for(i=0;i<10;i+ +)
a[i] = i;


for(i=0;i<10;i+ +)
printf("a[%d]= %d ",i,a[i]);

printf("\n");
printf("i=%d\n" ,i);

i++; /*Cause overflow!*/
a[i] = 10;/*Array overflow???*/

}

[Niklas Norrthon]

Re: Tool for detecting Array overflow

"slebetman@yaho o.com" <slebetman@gmai l.com> writes:
[color=blue]
> vashwath@rediff mail.com wrote:[color=green]
> >
> > Yes, I am using gcc for compilation.
> > I used the options you suggested for the following program
> >
> > #include <stdio.h>
> >
> > int main()
> > {
> > int a[10];
> >
> > int i;
> >
> > for(i=0;i<10;i+ +)
> > a[i] = i;
> >
> >
> > for(i=0;i<10;i+ +)
> > printf("a[%d]= %d ",i,a[i]);
> >
> > printf("\n");
> > printf("i=%d\n" ,i);
> >
> > a[i] = 10;/*Array overflow???*/
> >
> > }
> >
> > I gave the following command
> > gcc -w -Wall -fbounds-check arrBound.c
> >
> > But it did not detect the overflow.
> > Am i using the options correctly.[/color]
>
> In your code, I never exceed 9. So it did not detect overflow because
> there is no overflow. Just modify it with the following to cause
> overflow:[/color]

If that is the case, could you explain why the last printf
statement outputs "i=10"?

/Niklas Norrthon

[Igmar Palsenberg]

Re: Tool for detecting Array overflow

Bjørn Augestad wrote:[color=blue]
> On linux you can use valgrind, http://valgrind.kde.org.[/color]

Which doesn't detect overflows of arrays located on the stack.



Igmar

[saurabh]

Re: Tool for detecting Array overflow

Hi,

Try with this code: file name overflow.c

#include <stdlib.h>
#include <stdio.h>

int main ()
{
int arr[2] = {2,3,4};
}

On compiling with gcc version 3.4.2, I can see following compilation
error message,
gcc -fbounds-check overflow.c
overflow.c: In function `main':
overflow.c:6: warning: excess elements in array initializer
overflow.c6: warning: (near initialization for `arr')

Thanks & Regards,
Saurabh.


Igmar Palsenberg wrote:[color=blue]
> Bjørn Augestad wrote:[color=green]
> > On linux you can use valgrind, http://valgrind.kde.org.[/color]
>
> Which doesn't detect overflows of arrays located on the stack.
>
>
>
> Igmar[/color]

[slebetman@yahoo.com]

Re: Tool for detecting Array overflow

Niklas Norrthon wrote:[color=blue]
> "slebetman@yaho o.com" <slebetman@gmai l.com> writes:
>[color=green]
> > vashwath@rediff mail.com wrote:[color=darkred]
> > >
> > > Yes, I am using gcc for compilation.
> > > I used the options you suggested for the following program
> > >
> > > #include <stdio.h>
> > >
> > > int main()
> > > {
> > > int a[10];
> > >
> > > int i;
> > >
> > > for(i=0;i<10;i+ +)
> > > a[i] = i;
> > >
> > >
> > > for(i=0;i<10;i+ +)
> > > printf("a[%d]= %d ",i,a[i]);
> > >
> > > printf("\n");
> > > printf("i=%d\n" ,i);
> > >
> > > a[i] = 10;/*Array overflow???*/
> > >
> > > }
> > >
> > > I gave the following command
> > > gcc -w -Wall -fbounds-check arrBound.c
> > >
> > > But it did not detect the overflow.
> > > Am i using the options correctly.[/color]
> >
> > In your code, I never exceed 9. So it did not detect overflow because
> > there is no overflow. Just modify it with the following to cause
> > overflow:[/color]
>
> If that is the case, could you explain why the last printf
> statement outputs "i=10"?
>[/color]

Ah, sorry, I missed the fact that the i++ in the for loop does indeed
increment i to 10.