diff --git a/lib/common/output_html.c b/lib/common/output_html.c
index 1aa596ab43..4f2e1375b3 100644
--- a/lib/common/output_html.c
+++ b/lib/common/output_html.c
@@ -1,449 +1,450 @@
 /*
  * Copyright 2019-2021 the Pacemaker project contributors
  *
  * The version control history for this file may have further details.
  *
  * This source code is licensed under the GNU Lesser General Public License
  * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
  */
 
 #ifndef _GNU_SOURCE
 #  define _GNU_SOURCE
 #endif
 
 #include <ctype.h>
 #include <libxml/HTMLtree.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <stdio.h>
 
 #include <crm/crm.h>
 #include <crm/common/output_internal.h>
 #include <crm/common/xml.h>
 #include <crm/common/xml_internal.h>
 
 static const char *stylesheet_default =
     ".bold { font-weight: bold }\n"
     ".maint { color: blue }\n"
     ".offline { color: red }\n"
     ".online { color: green }\n"
     ".rsc-failed { color: red }\n"
     ".rsc-failure-ignored { color: yellow }\n"
     ".rsc-managed { color: yellow }\n"
     ".rsc-multiple { color: orange }\n"
     ".rsc-ok { color: green }\n"
     ".standby { color: orange }\n"
     ".warning { color: red, font-weight: bold }";
 
 static gboolean cgi_output = FALSE;
 static char *stylesheet_link = NULL;
 static char *title = NULL;
 static GSList *extra_headers = NULL;
 
 GOptionEntry pcmk__html_output_entries[] = {
     { "html-cgi", 0, 0, G_OPTION_ARG_NONE, &cgi_output,
       "Add CGI headers (requires --output-as=html)",
       NULL },
 
     { "html-stylesheet", 0, 0, G_OPTION_ARG_STRING, &stylesheet_link,
       "Link to an external stylesheet (requires --output-as=html)",
       "URI" },
 
     { "html-title", 0, 0, G_OPTION_ARG_STRING, &title,
       "Specify a page title (requires --output-as=html)",
       "TITLE" },
 
     { NULL }
 };
 
 typedef struct private_data_s {
     xmlNode *root;
     GQueue *parent_q;
     GSList *errors;
 } private_data_t;
 
 static void
 html_free_priv(pcmk__output_t *out) {
     private_data_t *priv = out->priv;
 
     if (priv == NULL) {
         return;
     }
 
     xmlFreeNode(priv->root);
     g_queue_free(priv->parent_q);
     g_slist_free(priv->errors);
     free(priv);
     out->priv = NULL;
 }
 
 static bool
 html_init(pcmk__output_t *out) {
     private_data_t *priv = NULL;
 
     /* If html_init was previously called on this output struct, just return. */
     if (out->priv != NULL) {
         return true;
     } else {
         out->priv = calloc(1, sizeof(private_data_t));
         if (out->priv == NULL) {
             return false;
         }
 
         priv = out->priv;
     }
 
     priv->parent_q = g_queue_new();
 
     priv->root = create_xml_node(NULL, "html");
     xmlCreateIntSubset(priv->root->doc, (pcmkXmlStr) "html", NULL, NULL);
 
     crm_xml_add(priv->root, "lang", "en");
     g_queue_push_tail(priv->parent_q, priv->root);
     priv->errors = NULL;
 
     pcmk__output_xml_create_parent(out, "body", NULL);
 
     return true;
 }
 
 static void
 add_error_node(gpointer data, gpointer user_data) {
     char *str = (char *) data;
     pcmk__output_t *out = (pcmk__output_t *) user_data;
     out->list_item(out, NULL, "%s", str);
 }
 
 static void
 html_finish(pcmk__output_t *out, crm_exit_t exit_status, bool print, void **copy_dest) {
     private_data_t *priv = out->priv;
     htmlNodePtr head_node = NULL;
     htmlNodePtr charset_node = NULL;
 
     /* If root is NULL, html_init failed and we are being called from pcmk__output_free
      * in the pcmk__output_new path.
      */
     if (priv == NULL || priv->root == NULL) {
         return;
     }
 
     if (cgi_output && print) {
         fprintf(out->dest, "Content-Type: text/html\n\n");
     }
 
     /* Add the head node last - it's not needed earlier because it doesn't contain
      * anything else that the user could add, and we want it done last to pick up
      * any options that may have been given.
      */
     head_node = xmlNewNode(NULL, (pcmkXmlStr) "head");
 
     if (title != NULL ) {
         pcmk_create_xml_text_node(head_node, "title", title);
     } else if (out->request != NULL) {
         pcmk_create_xml_text_node(head_node, "title", out->request);
     }
 
     charset_node = create_xml_node(head_node, "meta");
     crm_xml_add(charset_node, "charset", "utf-8");
 
     /* Add any extra header nodes the caller might have created. */
     for (int i = 0; i < g_slist_length(extra_headers); i++) {
         xmlAddChild(head_node, xmlCopyNode(g_slist_nth_data(extra_headers, i), 1));
     }
 
     /* Stylesheets are included two different ways.  The first is via a built-in
      * default (see the stylesheet_default const above).  The second is via the
      * html-stylesheet option, and this should obviously be a link to a
      * stylesheet.  The second can override the first.  At least one should be
      * given.
      */
     pcmk_create_xml_text_node(head_node, "style", stylesheet_default);
 
     if (stylesheet_link != NULL) {
         htmlNodePtr link_node = create_xml_node(head_node, "link");
         pcmk__xe_set_props(link_node, "rel", "stylesheet",
                            "href", stylesheet_link,
                            NULL);
     }
 
     xmlAddPrevSibling(priv->root->children, head_node);
 
     if (g_slist_length(priv->errors) > 0) {
         out->begin_list(out, "Errors", NULL, NULL);
         g_slist_foreach(priv->errors, add_error_node, (gpointer) out);
         out->end_list(out);
     }
 
     if (print) {
         htmlDocDump(out->dest, priv->root->doc);
     }
 
     if (copy_dest != NULL) {
         *copy_dest = copy_xml(priv->root);
     }
 
     g_slist_free_full(extra_headers, (GDestroyNotify) xmlFreeNode);
+    extra_headers = NULL;
 }
 
 static void
 html_reset(pcmk__output_t *out) {
     CRM_ASSERT(out != NULL);
 
     out->dest = freopen(NULL, "w", out->dest);
     CRM_ASSERT(out->dest != NULL);
 
     html_free_priv(out);
     html_init(out);
 }
 
 static void
 html_subprocess_output(pcmk__output_t *out, int exit_status,
                       const char *proc_stdout, const char *proc_stderr) {
     char *rc_buf = NULL;
     private_data_t *priv = out->priv;
     CRM_ASSERT(priv != NULL);
 
     rc_buf = crm_strdup_printf("Return code: %d", exit_status);
 
     pcmk__output_create_xml_text_node(out, "h2", "Command Output");
     pcmk__output_create_html_node(out, "div", NULL, NULL, rc_buf);
 
     if (proc_stdout != NULL) {
         pcmk__output_create_html_node(out, "div", NULL, NULL, "Stdout");
         pcmk__output_create_html_node(out, "div", NULL, "output", proc_stdout);
     }
     if (proc_stderr != NULL) {
         pcmk__output_create_html_node(out, "div", NULL, NULL, "Stderr");
         pcmk__output_create_html_node(out, "div", NULL, "output", proc_stderr);
     }
 
     free(rc_buf);
 }
 
 static void
 html_version(pcmk__output_t *out, bool extended) {
     private_data_t *priv = out->priv;
     CRM_ASSERT(priv != NULL);
 
     pcmk__output_create_xml_text_node(out, "h2", "Version Information");
     pcmk__output_create_html_node(out, "div", NULL, NULL, "Program: Pacemaker");
     pcmk__output_create_html_node(out, "div", NULL, NULL, crm_strdup_printf("Version: %s", PACEMAKER_VERSION));
     pcmk__output_create_html_node(out, "div", NULL, NULL, "Author: Andrew Beekhof");
     pcmk__output_create_html_node(out, "div", NULL, NULL, crm_strdup_printf("Build: %s", BUILD_VERSION));
     pcmk__output_create_html_node(out, "div", NULL, NULL, crm_strdup_printf("Features: %s", CRM_FEATURES));
 }
 
 G_GNUC_PRINTF(2, 3)
 static void
 html_err(pcmk__output_t *out, const char *format, ...) {
     private_data_t *priv = out->priv;
     int len = 0;
     char *buf = NULL;
     va_list ap;
 
     CRM_ASSERT(priv != NULL);
     va_start(ap, format);
     len = vasprintf(&buf, format, ap);
     CRM_ASSERT(len >= 0);
     va_end(ap);
 
     priv->errors = g_slist_append(priv->errors, buf);
 }
 
 G_GNUC_PRINTF(2, 3)
 static void
 html_info(pcmk__output_t *out, const char *format, ...) {
     /* This function intentially left blank */
 }
 
 static void
 html_output_xml(pcmk__output_t *out, const char *name, const char *buf) {
     htmlNodePtr node = NULL;
     private_data_t *priv = out->priv;
 
     CRM_ASSERT(priv != NULL);
 
     node = pcmk__output_create_html_node(out, "pre", NULL, NULL, buf);
     crm_xml_add(node, "lang", "xml");
 }
 
 G_GNUC_PRINTF(4, 5)
 static void
 html_begin_list(pcmk__output_t *out, const char *singular_noun,
                 const char *plural_noun, const char *format, ...) {
     int q_len = 0;
     private_data_t *priv = out->priv;
     xmlNodePtr node = NULL;
 
     CRM_ASSERT(priv != NULL);
 
     /* If we are already in a list (the queue depth is always at least
      * one because of the <html> element), first create a <li> element
      * to hold the <h2> and the new list.
      */
     q_len = g_queue_get_length(priv->parent_q);
     if (q_len > 2) {
         pcmk__output_xml_create_parent(out, "li", NULL);
     }
 
     if (format != NULL) {
         va_list ap;
         char *buf = NULL;
         int len;
 
         va_start(ap, format);
         len = vasprintf(&buf, format, ap);
         va_end(ap);
         CRM_ASSERT(len >= 0);
 
         if (q_len > 2) {
             pcmk__output_create_xml_text_node(out, "h3", buf);
         } else {
             pcmk__output_create_xml_text_node(out, "h2", buf);
         }
 
         free(buf);
     }
 
     node = pcmk__output_xml_create_parent(out, "ul", NULL);
     g_queue_push_tail(priv->parent_q, node);
 }
 
 G_GNUC_PRINTF(3, 4)
 static void
 html_list_item(pcmk__output_t *out, const char *name, const char *format, ...) {
     private_data_t *priv = out->priv;
     htmlNodePtr item_node = NULL;
     va_list ap;
     char *buf = NULL;
     int len;
 
     CRM_ASSERT(priv != NULL);
 
     va_start(ap, format);
     len = vasprintf(&buf, format, ap);
     CRM_ASSERT(len >= 0);
     va_end(ap);
 
     item_node = pcmk__output_create_xml_text_node(out, "li", buf);
     free(buf);
 
     if (name != NULL) {
         crm_xml_add(item_node, "class", name);
     }
 }
 
 static void
 html_increment_list(pcmk__output_t *out) {
     /* This function intentially left blank */
 }
 
 static void
 html_end_list(pcmk__output_t *out) {
     private_data_t *priv = out->priv;
 
     CRM_ASSERT(priv != NULL);
 
     /* Remove the <ul> tag. */
     g_queue_pop_tail(priv->parent_q);
     pcmk__output_xml_pop_parent(out);
 
     /* Remove the <li> created for nested lists. */
     if (g_queue_get_length(priv->parent_q) > 2) {
         pcmk__output_xml_pop_parent(out);
     }
 }
 
 static bool
 html_is_quiet(pcmk__output_t *out) {
     return false;
 }
 
 static void
 html_spacer(pcmk__output_t *out) {
     pcmk__output_create_xml_node(out, "br", NULL);
 }
 
 static void
 html_progress(pcmk__output_t *out, bool end) {
     /* This function intentially left blank */
 }
 
 pcmk__output_t *
 pcmk__mk_html_output(char **argv) {
     pcmk__output_t *retval = calloc(1, sizeof(pcmk__output_t));
 
     if (retval == NULL) {
         return NULL;
     }
 
     retval->fmt_name = "html";
     retval->request = argv == NULL ? NULL : g_strjoinv(" ", argv);
 
     retval->init = html_init;
     retval->free_priv = html_free_priv;
     retval->finish = html_finish;
     retval->reset = html_reset;
 
     retval->register_message = pcmk__register_message;
     retval->message = pcmk__call_message;
 
     retval->subprocess_output = html_subprocess_output;
     retval->version = html_version;
     retval->info = html_info;
     retval->err = html_err;
     retval->output_xml = html_output_xml;
 
     retval->begin_list = html_begin_list;
     retval->list_item = html_list_item;
     retval->increment_list = html_increment_list;
     retval->end_list = html_end_list;
 
     retval->is_quiet = html_is_quiet;
     retval->spacer = html_spacer;
     retval->progress = html_progress;
     retval->prompt = pcmk__text_prompt;
 
     return retval;
 }
 
 xmlNodePtr
 pcmk__output_create_html_node(pcmk__output_t *out, const char *element_name, const char *id,
                        const char *class_name, const char *text) {
     htmlNodePtr node = pcmk__output_create_xml_text_node(out, element_name, text);
 
     if (class_name != NULL) {
         crm_xml_add(node, "class", class_name);
     }
 
     if (id != NULL) {
         crm_xml_add(node, "id", id);
     }
 
     return node;
 }
 
 void
 pcmk__html_add_header(const char *name, ...) {
     htmlNodePtr header_node;
     va_list ap;
 
     va_start(ap, name);
 
     header_node = xmlNewNode(NULL, (pcmkXmlStr) name);
     while (1) {
         char *key = va_arg(ap, char *);
         char *value;
 
         if (key == NULL) {
             break;
         }
 
         value = va_arg(ap, char *);
         crm_xml_add(header_node, key, value);
     }
 
     extra_headers = g_slist_append(extra_headers, header_node);
 
     va_end(ap);
 }