You're not making any sense: I already wrote "protect against buffer overflow instead of integer overflow" and your response is "buffer overflow".

Integer overflow can be a causal cause of buffer overflow. Like this for example:

  read(fd, &header, sizeof(header));
  int total_len = header.data_len + header.code_len;
  char *data = malloc(total_len);
  read(fd, data, total_len);

Now, the attacker crafts the file and.. there's your buffer overflow which is a direct consequence of undetected integer overflow [i.e., the program being allowed to proceed].

Once again: if you protect against buffer overflow, an integer overflow that might lead to buffer overflow doesn't matter. The C example doesn't matter because C has neither.