 void buffer_slow_realign(struct buffer *buf)
 {
       /* two possible cases :
        *   - the buffer is in one contiguous block, we move it in-place
        *   - the buffer is in two blocks, we move it via the swap_buffer
        */
       if (buf->i) {
               int block1 = buf->i;
               int block2 = 0;
               if (buf->p + buf->i > buf->data + buf->size) {
                       /* non-contiguous block */
                       block1 = buf->data + buf->size - buf->p;
                       block2 = buf->p + buf->i - (buf->data + buf->size);
               }
               if (block2)
                       memcpy(swap_buffer, buf->data, block2);
               memmove(buf->data, buf->p, block1);
               if (block2)
                       memcpy(buf->data + block1, swap_buffer, block2);
        }
 
        buf->p = buf->data;
 }

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.