remove the ASSERT warning in UEFI mode when boot fail.

EDK2/edk2_mod/edk2-edk2-stable201911/MdeModulePkg/Application/Ventoy/Ventoy.c

@@ -42,6 +42,7 @@ BOOLEAN gLoadIsoEfi = FALSE;
 BOOLEAN gIsoUdf = FALSE;
 ventoy_ram_disk g_ramdisk_param;
 ventoy_chain_head *g_chain;
+void *g_vtoy_img_location_buf;
 ventoy_img_chunk *g_chunk;
 UINT8 *g_os_param_reserved;
 UINT32 g_img_chunk_num;
@@ -269,6 +270,7 @@ static int ventoy_update_image_location(ventoy_os_param *param)
     }
 
     address = (UINTN)buffer;
+    g_vtoy_img_location_buf = buffer;
 
     if (address % 4096)
     {
@@ -873,12 +875,15 @@ EFI_STATUS EFIAPI ventoy_clean_env(VOID)
 
     ventoy_delete_variable();
 
-    if (g_chain->os_param.vtoy_img_location_addr)
+    if (g_vtoy_img_location_buf)
     {
-        FreePool((VOID *)(UINTN)g_chain->os_param.vtoy_img_location_addr);
+        FreePool(g_vtoy_img_location_buf);
     }
 
-    FreePool(g_chain);
+    if (!gMemdiskMode)
+    {
+        FreePool(g_chain);        
+    }
 
     return EFI_SUCCESS;
 }