What can go wrong in following code?

#include  
int main(int argc, char *argv[]){
    if(argc != 3){
        printf("usage: %s [source] [dest]n", argv[0]);
        exit(1);
    }
    char buffer1[5];
    strcpy(buffer1, argv[1]);
    char buffer2[5];
    strcpy(buffer1, argv[1]);
    char x;
    FILE *file[2];
    file[0] = fopen(buffer1,"r+");
    file[1] = fopen(buffer2,"w+");
    for(x = 0; x < 2; x++){
        if(file[x] == NULL){
            printf("error opening file.n");
            exit(1);
        }
    }
    do {
        x = fgetc(file[0]);
        fputc(x,file[1]);
    }
    while(x != EOF);
    for(x = 0; x < 2; x++)         
        fclose(file[x]);
    return 0;
}

The fixed-size stack buffers (buffer1[5], buffer2[5]) are filled via strcpy from argv[1] with no length check, so any command-line argument longer than 4 characters overflows the buffer and can corrupt the stack — a classic buffer overflow. Because a stack buffer overflow can be leveraged to overwrite a return address and redirect execution into existing code (e.g., a libc function), it also enables arc/return-oriented injection, which is why 'both' buffer overflow and arc injection apply.

• Thanks
• Wrong explanation