void reverseList(ListNode* startOfSec, ListNode *endOfSec){

    ListNode *prev = NULL;
    ListNode *curr = startOfSec;
    ListNode *nxt;
    while(curr!=endOfSec->next){
        nxt = curr->next;
        curr->next = prev;
        prev = curr;
        curr = nxt;
    }
}

Callsite:
//code to get start and end pointers
reverseList(start, end);