OD:

 1 #include<stdio.h>
 2 #include<string.h>
 3 #define PASSWORD "1234567"
 4 
 5 int verify_password(char *password)
 6 {
 7     int authenticated;
 8     char buffer[8];     // add local buf to be overflowed
 9     authenticated=strcmp(password,PASSWORD);
10     strcpy(buffer, password);  // overflow here
11     return authenticated;
12 }
13 
14 int main()
15 {
16     int valid_flag=0;
17     char password[1024];
18     while(1){
19         printf("Please input password: ");
20         scanf("%s",password);
21         valid_flag=verify_password(password);
22         if(valid_flag){
23             printf("Incorrect password!\n\n");
24         }
25         else
26         {
27             printf("Congratulation! You have passed the verification!\n\n\n");
28             break;
29         }
30     }
31     return 0;
32 }