From 917344cf17042680a67f4dce680dd0f7b269e183 Mon Sep 17 00:00:00 2001
From: shermp <14854761+shermp@users.noreply.github.com>
Date: Sat, 15 Jun 2019 16:22:29 +1200
Subject: [PATCH] Guard against NULL pointer dereference in mvhd_close

---
 src/minivhd_manage.c | 36 +++++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/src/minivhd_manage.c b/src/minivhd_manage.c
index 083098c..9900e44 100644
--- a/src/minivhd_manage.c
+++ b/src/minivhd_manage.c
@@ -540,24 +540,26 @@ end:
  * \param [in] vhdm MiniVHD data structure to close
  */
 void mvhd_close(MVHDMeta* vhdm) {
-    if (vhdm->parent != NULL) {
-        mvhd_close(vhdm->parent);
+    if (vhdm != NULL) {
+        if (vhdm->parent != NULL) {
+            mvhd_close(vhdm->parent);
+        }
+        fclose(vhdm->f);
+        if (vhdm->block_offset != NULL) {
+            free(vhdm->block_offset);
+            vhdm->block_offset = NULL;
+        }
+        if (vhdm->bitmap.curr_bitmap != NULL) {
+            free(vhdm->bitmap.curr_bitmap);
+            vhdm->bitmap.curr_bitmap = NULL;
+        }
+        if (vhdm->format_buffer.zero_data != NULL) {
+            free(vhdm->format_buffer.zero_data);
+            vhdm->format_buffer.zero_data = NULL;
+        }
+        free(vhdm);
+        vhdm = NULL;
     }
-    fclose(vhdm->f);
-    if (vhdm->block_offset != NULL) {
-        free(vhdm->block_offset);
-        vhdm->block_offset = NULL;
-    }
-    if (vhdm->bitmap.curr_bitmap != NULL) {
-        free(vhdm->bitmap.curr_bitmap);
-        vhdm->bitmap.curr_bitmap = NULL;
-    }
-    if (vhdm->format_buffer.zero_data != NULL) {
-        free(vhdm->format_buffer.zero_data);
-        vhdm->format_buffer.zero_data = NULL;
-    }
-    free(vhdm);
-    vhdm = NULL;
 }
 
 /**