Fix multiple errors with destructors.

This commits cleans up 3 segfaults/valgrind errors due to access
to freed memory.

1. The spy wasn't clearing conn_spy causing the svc_destructor to try
   to clear the spy destructor when the spy was already freed

2. get_config_service was not setting the svc_destrcutor on services
   depending on the orderof frees at exit this was causing the spy
   destructor to try to access freed memory because it was not
   neutralized when the service was freed.

3. at exit the mt_ctx could be freed before services causing the
   svc_destrcutor to try to access freed memory when removing the
   service from the service list in the monitor context.

1 files changed, 22 insertions, 2 deletions

diff --git a/src/monitor/monitor.c b/src/monitor/monitor.c
index c6af60612..ddf3de91f 100644
--- a/src/monitor/monitor.c
+++ b/src/monitor/monitor.c
@@ -282,8 +282,10 @@ static int svc_destructor(void *mem)
         return 0;
     }
 
-    /* always try to delist service */
-    DLIST_REMOVE(svc->mt_ctx->svc_list, svc);
+    /* try to delist service */
+    if (svc->mt_ctx) {
+        DLIST_REMOVE(svc->mt_ctx->svc_list, svc);
+    }
 
     /* svc is beeing freed, neutralize the spy */
     if (svc->conn_spy) {
@@ -302,6 +304,7 @@ static int svc_spy_destructor(void *mem)
     }
 
     /* svc->conn has been freed, NULL the pointer in svc */
+    spy->svc->conn_spy = NULL;
     spy->svc->conn = NULL;
     return 0;
 }
@@ -886,6 +889,8 @@ static int get_service_config(struct mt_ctx *ctx, const char *name,
     }
     svc->mt_ctx = ctx;
 
+    talloc_set_destructor((TALLOC_CTX *)svc, svc_destructor);
+
     svc->name = talloc_strdup(svc, name);
     if (!svc->name) {
         talloc_free(svc);
@@ -1196,6 +1201,20 @@ int read_config_file(const char *config_file)
     return ret;
 }
 
+static int monitor_ctx_destructor(void *mem)
+{
+    struct mt_ctx *mon = talloc_get_type(mem, struct mt_ctx);
+    struct mt_svc *svc;
+
+    /* zero out references in svcs so that they don't try
+     * to access the monitor context on process shutdown */
+
+    for (svc = mon->svc_list; svc; svc = svc->next) {
+        svc->mt_ctx = NULL;
+    }
+    return 0;
+}
+
 static errno_t load_configuration(TALLOC_CTX *mem_ctx,
                                   const char *config_file,
                                   struct mt_ctx **monitor)
@@ -1208,6 +1227,7 @@ static errno_t load_configuration(TALLOC_CTX *mem_ctx,
     if(!ctx) {
         return ENOMEM;
     }
+    talloc_set_destructor((TALLOC_CTX *)ctx, monitor_ctx_destructor);
 
     cdb_file = talloc_asprintf(ctx, "%s/%s", DB_PATH, CONFDB_FILE);
     if (cdb_file == NULL) {