HPCC-20677 Index distribute using wrong base helper, could crash

Signed-off-by: Jake Smith <jake.smith@lexisnexisrisk.com>

thorlcr/activities/hashdistrib/thhashdistribslave.cpp

@@ -1988,8 +1988,6 @@ public:
     HashDistributeSlaveBase(CGraphElementBase *_container)
         : CSlaveActivity(_container)
     {
-        IHThorHashDistributeArg *distribargs = (IHThorHashDistributeArg *)queryHelper();
-        ihash = distribargs->queryHash();
         appendOutputLinked(this);
     }
     ~HashDistributeSlaveBase()
@@ -2089,18 +2087,22 @@ public:
 
 class HashDistributeSlaveActivity : public HashDistributeSlaveBase
 {
+    typedef HashDistributeSlaveBase PARENT;
 public:
-    HashDistributeSlaveActivity(CGraphElementBase *container) : HashDistributeSlaveBase(container)
+    HashDistributeSlaveActivity(CGraphElementBase *container) : PARENT(container)
     {
+        IHThorHashDistributeArg *distribargs = (IHThorHashDistributeArg *)queryHelper();
+        ihash = distribargs->queryHash();
     }
 };
 
 //===========================================================================
 
-class HashDistributeMergeSlaveActivity : public HashDistributeSlaveBase
+class HashDistributeMergeSlaveActivity : public HashDistributeSlaveActivity
 {
+    typedef HashDistributeSlaveActivity PARENT;
 public:
-    HashDistributeMergeSlaveActivity(CGraphElementBase *container) : HashDistributeSlaveBase(container)
+    HashDistributeMergeSlaveActivity(CGraphElementBase *container) : PARENT(container)
     {
         IHThorHashDistributeArg *distribargs = (IHThorHashDistributeArg *)queryHelper();
         mergecmp = distribargs->queryMergeCompare();
@@ -2327,16 +2329,16 @@ public:
 };
 
 
-class ReDistributeSlaveActivity : public HashDistributeSlaveBase
+class ReDistributeSlaveActivity : public HashDistributeSlaveActivity
 {
-    typedef HashDistributeSlaveBase PARENT;
+    typedef HashDistributeSlaveActivity PARENT;
 
     Owned<CHDRproportional> partitioner;
 public:
-    ReDistributeSlaveActivity(CGraphElementBase *container) : HashDistributeSlaveBase(container) { }
+    ReDistributeSlaveActivity(CGraphElementBase *container) : PARENT(container) { }
     virtual void init(MemoryBuffer &data, MemoryBuffer &slaveData) override
     {
-        HashDistributeSlaveBase::init(data, slaveData);
+        PARENT::init(data, slaveData);
         mptag_t tag = container.queryJobChannel().deserializeMPTag(data);
         IHThorHashDistributeArg *distribargs = (IHThorHashDistributeArg *)queryHelper();
         partitioner.setown(new CHDRproportional(this, distribargs,tag));
@@ -2358,7 +2360,7 @@ public:
     }
     virtual void stop() override
     {
-        HashDistributeSlaveBase::stop();
+        PARENT::stop();
         if (instrm)
             instrm.clear(); // should remove here rather than later?
     }
@@ -2368,6 +2370,8 @@ public:
 
 class IndexDistributeSlaveActivity : public HashDistributeSlaveBase
 {
+    typedef HashDistributeSlaveBase PARENT;
+
     class CKeyLookup : implements IHash
     {
         IndexDistributeSlaveActivity &owner;
@@ -2397,7 +2401,7 @@ class IndexDistributeSlaveActivity : public HashDistributeSlaveBase
     } *lookup;
 
 public:
-    IndexDistributeSlaveActivity(CGraphElementBase *container) : HashDistributeSlaveBase(container), lookup(NULL)
+    IndexDistributeSlaveActivity(CGraphElementBase *container) : PARENT(container), lookup(NULL)
     {
     }
     ~IndexDistributeSlaveActivity()
@@ -2407,7 +2411,7 @@ public:
     }
     virtual void init(MemoryBuffer &data, MemoryBuffer &slaveData) override
     {
-        HashDistributeSlaveBase::init(data, slaveData);
+        PARENT::init(data, slaveData);
 
         IHThorKeyedDistributeArg *helper = (IHThorKeyedDistributeArg *) queryHelper();