void main(int argn, char **args) 
{
  char buff[32]; 

  // overflow occurs when argument
  // length is greater than 32 characters
  strcpy(buff,args[1]); 
  ...
}

C library functions such as strcpy(), strcat(), sprintf() and vsprintf() operate on null terminated strings and perform no bounds checking. gets() is another function that reads user input (into a buffer) from stdin until a terminating newline or EOF is found. The scanf() family of functions also may result in buffer overflows. Hence, the best way to deal with buffer overflow problems is to not allow them to occur in the first place.

#define MAX (((a)>(b))?(a):(b))
void main(int argn, char **args) 
{
  // buff is initialized with '\0'
  static char buff[32]; 

  // safer
  strncpy(buff,MAX(31,strlen(args[1])); 
  ...
}