Fixing a sample from K&R book using cake static analyser

In this video ( https://youtu.be/ZZCKPKzNUCQ
) I show step by step how removing warnings will fix a memory leak.
Page 145, The C programming Language 2 Edition
/* install:  put (name, defn) in hashtab */
struct nlist *install(char *name, char *defn)
{
     struct nlist *np;
     unsigned hashval;
     if ((np = lookup(name)) == NULL) {  /* not found */
         np = (struct nlist *) malloc(sizeof(*np));
         if (np == NULL || (np->name = strdup(name)) == NULL)
             return NULL;
         hashval = hash(name);
         np->next = hashtab[hashval];
         hashtab[hashval] = np;
     } else      /* already there */
         free((void *) np->defn);  /* free previous defn */
     if ((np->defn = strdup(defn)) == NULL)
         return NULL;
     return np;
}
The concepts used are
  - ownership transfer
  - nullable pointers
Concepts are described here
http://thradams.com/cake/ownership.html
To see the sample and play with it:
http://thradams.com/cake/playground.html
Select "find the bug" and "bug #7 K & R"