Prevent segmentation fault in buffer overflow demonstration in Ubuntu 12

Question

I am trying to run this piece of vulnerable C code:

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

int add(int x, int y)
{
 int z =10;
 z = x + y;
 return z;
}

main(int argc, char **argv)
{
 int a = atoi(argv[1]);
 int b = atoi(argv[2]);
 int c;

 char buffer[100];

 gets(buffer);
 puts(buffer);

 c = add(a,b);

 printf("Sum of %d+%d = %d\n",a, b, c);

 exit(0);
}

I am trying to get past the segmentation fault so that I can input the integers but the segmentation fault prevents that. In the terminal I have tried: gcc -ggdb -fno-stack-protector -U_FORTIFY_SOURCE -Wa,--execstack -o SimpleDemo SimpleDemo.c

I still get a segmentation fault. I am lost as to what to try next. As you can probably tell, I am an ubuntu newb. The bash code I am using comes from here:

http://www.evanjones.ca/buffer-overflow-101.html

I have been at this for while so would really appreciate some help

Cheers

You need to provide the integers as command-line arguments, not run the program and then enter them. If you don't, the atoi(argv[1]) call will seg fault (probably). — hmjd
– hmjd, Commented Jun 26, 2012 at 15:58

Uday · Accepted Answer · 2012-06-26 18:58:25Z

1

Just explaining what hmjd is asking you to do.

Run (binary) 10 20

answered Jun 26, 2012 at 18:58

Uday

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1 Comment

SunnyNewb Over a year ago

Thanks guys. Just to clarify, when I run the program with - ./SimpleDemo, I put 10 and 20 on that line? How would the bash code to run this look?

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