knownhosts: Fix possible null pointer dereference

CID 1391447

Signed-off-by: Andreas Schneider <asn@cryptomilk.org>

src/knownhosts.c

@@ -403,12 +403,14 @@ int ssh_known_hosts_parse_line(const char *hostname,
     p = strtok(NULL, " ");
     if (p != NULL) {
         p = strstr(line, p);
+        if (p != NULL) {
             e->comment = strdup(p);
             if (e->comment == NULL) {
                 rc = SSH_ERROR;
                 goto out;
             }
         }
+    }
 
     *entry = e;
     SAFE_FREE(known_host);