From a7886e7a44582fbc019e995afa2147eb0efd6710 Mon Sep 17 00:00:00 2001
From: Oliver Kurth <okurth@vmware.com>
Date: Fri, 15 Sep 2017 11:23:30 -0700
Subject: [PATCH] Fixed invalid class pointer access if VSS provider not
 installed

Some customers may disable VSS support by not installing VMware snapshot
provider, which may lead to the VSS provider not being able to be
initialized, which in turn could lead to a invalid class pointer access
during complete initialization.

This change checks provider initialization status before initialize
completer to fix the issue.
---
 .../services/plugins/vmbackup/stateMachine.c  | 47 ++++++++++++-------
 1 file changed, 30 insertions(+), 17 deletions(-)

diff --git a/open-vm-tools/services/plugins/vmbackup/stateMachine.c b/open-vm-tools/services/plugins/vmbackup/stateMachine.c
index 2a7b16df7..5f530dd2f 100644
--- a/open-vm-tools/services/plugins/vmbackup/stateMachine.c
+++ b/open-vm-tools/services/plugins/vmbackup/stateMachine.c
@@ -86,6 +86,8 @@ VM_EMBED_VERSION(VMTOOLSD_VERSION_STRING);
 #define VMBACKUP_CONFIG_GET_INT(config, key, defVal)        \
    VMTools_ConfigGetInteger(config, "vmbackup", key, defVal)
 
+#define VMBACKUP_CFG_ENABLEVSS      "enableVSS"
+
 static VmBackupState *gBackupState = NULL;
 
 static Bool
@@ -871,7 +873,7 @@ VmBackupStartCommon(RpcInData *data,
       const gchar *cfgEntry;
    } providers[] = {
 #if defined(_WIN32)
-      { VmBackup_NewVssProvider, "enableVSS" },
+      { VmBackup_NewVssProvider, VMBACKUP_CFG_ENABLEVSS},
 #endif
       { VmBackup_NewSyncDriverProvider, "enableSyncDriver" },
       { VmBackup_NewNullProvider, NULL },
@@ -884,8 +886,17 @@ VmBackupStartCommon(RpcInData *data,
           * only allow VSS provider
           */
 #if defined(_WIN32)
-         if (VMBACKUP_CONFIG_GET_BOOL(ctx->config, "enableVSS", TRUE)) {
+         if (VMBACKUP_CONFIG_GET_BOOL(ctx->config,
+                                      VMBACKUP_CFG_ENABLEVSS, TRUE)) {
             provider = VmBackup_NewVssProvider();
+            if (provider != NULL) {
+               completer = VmBackup_NewVssCompleter(provider);
+               if (completer == NULL) {
+                  g_warning("VSS completion helper cannot be initialized.");
+                  provider->release(provider);
+                  provider = NULL;
+               }
+            }
          }
 #elif defined(_LINUX) || defined(__linux__)
          /*
@@ -901,10 +912,6 @@ VmBackupStartCommon(RpcInData *data,
          /* If no quiescing is requested only allow null provider */
          provider = VmBackup_NewNullProvider();
       }
-      if (provider == NULL) {
-         g_warning("Requested quiescing cannot be initialized.");
-         goto error;
-      }
    } else {
       /* Instantiate the sync provider. */
       for (i = 0; i < ARRAYSIZE(providers); i++) {
@@ -913,24 +920,30 @@ VmBackupStartCommon(RpcInData *data,
          if (VMBACKUP_CONFIG_GET_BOOL(ctx->config, sp->cfgEntry, TRUE)) {
             provider = sp->ctor();
             if (provider != NULL) {
+#if defined(_WIN32)
+               if (sp->cfgEntry != NULL &&
+                   Str_Strcmp(sp->cfgEntry, VMBACKUP_CFG_ENABLEVSS) == 0) {
+                  completer = VmBackup_NewVssCompleter(provider);
+                  if (completer == NULL) {
+                     g_warning("VSS completion helper cannot be initialized.");
+                     provider->release(provider);
+                     provider = NULL;
+                     continue;
+                  }
+                  break;
+               }
+#else
                break;
+#endif
             }
          }
       }
    }
 
-   ASSERT(provider != NULL);
-
-#if defined(_WIN32)
-   if (VMBACKUP_CONFIG_GET_BOOL(ctx->config, "enableVSS", TRUE)) {
-      completer = VmBackup_NewVssCompleter(provider);
-      if (completer == NULL) {
-         provider->release(provider);
-         g_warning("Requested quiescing cannot be initialized.");
-         goto error;
-      }
+   if (provider == NULL) {
+      g_warning("Requested quiescing cannot be initialized.");
+      goto error;
    }
-#endif
 
    /* Instantiate the backup state and start the operation. */
    gBackupState->ctx = data->appCtx;
-- 
2.47.3