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Buffer Overflow Basics
By: Suhas Desai
A buffer overflow occurs when a program or process tries to store more data in a temporary data storage area than it was intended to hold. Since buffers are created to contain a finite amount of data, the extra information can overflow into adjacent buffers, corrupting or overwriting the valid data held in them.
Buffer overflows are a fertile source of bugs and malicious attacks. They occur when a program attempts to write data past the end of a buffer. A buffer is a contiguous allocated chunk of memory, such as an array or pointer in C. Limitation of C and C++ is there are no automatic bounds checking on the buffer where user can write past a buffer as given in example.
Note: All examples are compiled on Linux platform having x86 configuration.
int main ()
{
int buffer [10];
buffer[20]=10;
}
After execution of this program it won’t give errors but program attempts to write beyond the allocated memory for the buffer which results for unexpected output.
void function (char *str)
{
char buffer[16];
strcpy(buffer,str);
}
int main()
{
char *str=
