fix missing err check in the commit path #1543

cendhu · 2020-07-07T08:34:27Z

Type of change

Bug fix

Description

This PR addresses some of the missing err check in the ledger commit path.

Additional details

A careful analysis must be done to ensure that this PR is not creating a possibility of a fork.

Signed-off-by: senthil <[email protected]>

cendhu · 2020-07-15T10:47:36Z

core/ledger/kvledger/txmgmt/queryutil/iterator_combiner.go

@@ -67,7 +67,9 @@ func (combiner *itrCombiner) Next() (commonledger.QueryResult, error) {
 		}
 	}
 	kv := combiner.kvAt(smallestHolderIndex)
-	combiner.moveItrAndRemoveIfExhausted(smallestHolderIndex)
+	if _, err := combiner.moveItrAndRemoveIfExhausted(smallestHolderIndex); err != nil {


an err can happen here due leveldb internal error (i.e., iter.Next()). As this error is related to the system resources and does not change depending on the block content, there is no possibility of a fork.

cendhu · 2020-07-15T10:57:52Z

core/ledger/kvledger/txmgmt/rwsetutil/query_results_helper.go

@@ -106,7 +106,10 @@ func (helper *RangeQueryResultsHelper) Done() ([]*kvrwset.KVRead, *kvrwset.Query
 			return helper.pendingResults, nil, err
 		}
 	}
-	helper.mt.done()
+	if err := helper.mt.done(); err != nil {


An err can happen here only when the hash computation returns an error., i.e., either GetHash() or hash.Write(). Given that this error would not change with respect to the block content, no possibility of a fork.

cendhu · 2020-07-15T11:06:26Z

core/ledger/kvledger/txmgmt/rwsetutil/query_results_helper.go

-	helper.mt.update(hash)
-	return nil
+	// TODO: Need to analyze any fork possibilities.
+	return helper.mt.update(hash)


Same as the helper.mt.done()

cendhu · 2020-07-15T11:08:23Z

core/ledger/kvledger/txmgmt/txmgr/lockbased_txmgr.go

@@ -106,7 +106,9 @@ func NewLockBasedTxMgr(initializer *Initializer) (*LockBasedTxMgr, error) {
 		return nil, errors.New("create new lock based TxMgr failed: passed in nil ledger hasher")
 	}

-	initializer.DB.Open()
+	if err := initializer.DB.Open(); err != nil {


Open() always return a nil and it is a nop. We can remove this API in a separate PR.

cendhu · 2020-07-15T11:22:10Z

core/ledger/kvledger/txmgmt/validation/rangequery_validator.go

@@ -119,7 +119,10 @@ func (v *rangeQueryHashValidator) validate() (bool, error) {
 			return equals, nil
 		}
 		versionedKV := result.(*statedb.VersionedKV)
-		v.resultsHelper.AddResult(rwsetutil.NewKVRead(versionedKV.Key, versionedKV.Version))
+		if err := v.resultsHelper.AddResult(rwsetutil.NewKVRead(versionedKV.Key, versionedKV.Version)); err != nil {


An err can happen here only if either the proto marshal fails or the hash function returns an error. As the validator reads the value from the DB, the content of the block should not change the result. Hence, there is no possibility of a fork here.

I'll summarize it a bit differently... Though, practically its a remote chance, but theoretically, this error miss could already cause a fork, as per the existing code. Because, the peer that would miss this error will continue with evaluating the results further and will eventually find the query results different and hence will mark the transaction invalid. Now, this change, instead of marking the transaction invalid, will cause a panic in upstream - So, this should be an acceptable change without an additional capability check.

On a side note, having said the above, I see the possibility of this error getting generated only if someone is using HSM for hash computation. Because, golang's crypto hash library does not return error. Also, as you mentioned the other possibility of the error is the proto marshal down stream, which is only possible if there would have been a programming error in our code, potentially passing nil (which is not happening here)

cendhu · 2020-07-15T11:37:35Z

core/ledger/kvledger/kv_ledger.go

-	l.pvtdataStore.ResetLastUpdatedOldBlocksList()
-
-	return nil
+	return l.pvtdataStore.ResetLastUpdatedOldBlocksList()


An err can occur due to a leveldb internal error. Further, this is part of the peer recovery code and executes during the peer startup. Hence, it is safe to process this error and it would not create any fork or make difficulties in joining a new peer (which would fetch and process all blocks). A leveldb error during the peer startup would result in a peer panic and is the expected behavior.

cendhu · 2020-07-15T11:43:06Z

core/ledger/kvledger/txmgmt/pvtstatepurgemgmt/purge_mgr.go

@@ -78,7 +78,9 @@ func (p *PurgeMgr) UpdateExpiryInfoOfPvtDataOfOldBlocks(pvtUpdates *privacyenabl
 	builder := newExpiryScheduleBuilder(p.btlPolicy)
 	pvtUpdateCompositeKeyMap := pvtUpdates.ToCompositeKeyMap()
 	for k, vv := range pvtUpdateCompositeKeyMap {
-		builder.add(k.Namespace, k.CollectionName, k.Key, util.ComputeStringHash(k.Key), vv)
+		if err := builder.add(k.Namespace, k.CollectionName, k.Key, util.ComputeStringHash(k.Key), vv); err != nil {


An err can occur here while retrieving collection info (NoSuchCollectionError or DB read error). At this point, NoSuchCollectionError error would not occur because the private data coordinator return err (which eventually results in peer panic) if a collection does not exist. Hence, an err can happen here only due to DB access. For DB access error, peer panic would occur, and no forks possibility as such.

I guess that you mistakenly linked this function to the regular commit path. This function is for old missing pvt data which is in the reconciliation path and does cause a panic but rather retries.

Ah. Correct. My mistake.

cendhu · 2020-07-15T13:24:45Z

core/ledger/pvtdatastorage/helper.go

@@ -78,12 +78,16 @@ func prepareExpiryEntries(committingBlk uint64, dataEntries []*dataEntry, missin

 	// 1. prepare expiryData for non-missing data
 	for _, dataEntry := range dataEntries {
-		prepareExpiryEntriesForPresentData(mapByExpiringBlk, dataEntry.key, btlPolicy)
+		if err := prepareExpiryEntriesForPresentData(mapByExpiringBlk, dataEntry.key, btlPolicy); err != nil {


An err can occur here only if the collection does not exist or if DB access results in an error. As NoSuchCollectionError is not possible here, it is safe to process DB access error and it would not cause a fork.

cendhu · 2020-07-15T13:24:56Z

core/ledger/pvtdatastorage/helper.go

 	}

 	// 2. prepare expiryData for missing data
 	for missingDataKey := range missingDataEntries {
-		prepareExpiryEntriesForMissingData(mapByExpiringBlk, &missingDataKey, btlPolicy)
+		if err := prepareExpiryEntriesForMissingData(mapByExpiringBlk, &missingDataKey, btlPolicy); err != nil {


Same as above.

cendhu · 2020-07-15T13:25:32Z

core/ledger/pvtdatastorage/store.go

@@ -776,7 +776,9 @@ func (s *Store) purgeExpiredData(minBlkNum, maxBlkNum uint64) error {
 		for _, missingDataKey := range missingDataKeys {
 			batch.Delete(encodeMissingDataKey(missingDataKey))
 		}
-		s.db.WriteBatch(batch, false)
+		if err := s.db.WriteBatch(batch, false); err != nil {
+			return err


Only results in a warning message.

manish-sethi · 2020-07-16T00:07:27Z

@cendhu - thanks for catching these. I am still looking at 2/3 of these more closely to understand the fallout a bit better.
Also, I guess we should perhaps add errcheck linter in CI.

manish-sethi

In order to take notes, I have made a few representative comments. The rest of the errors miss cases are either of these (or not affecting the critical path)

manish-sethi · 2020-07-16T03:07:47Z

core/ledger/kvledger/txmgmt/validation/tx_ops.go

@@ -18,8 +18,9 @@ import (
 func prepareTxOps(rwset *rwsetutil.TxRwSet, txht *version.Height,
 	precedingUpdates *publicAndHashUpdates, db *privacyenabledstate.DB) (txOps, error) {
 	txops := txOps{}
-	txops.applyTxRwset(rwset)
-	//logger.Debugf("prepareTxOps() txops after applying raw rwset=%#v", spew.Sdump(txops))
+	if err := txops.applyTxRwset(rwset); err != nil {


Rather, in the current code, the error miss could have caused a state fork (because of missing applying the metadata). Now, instead, this would cause panic in the upstream code instead of committing the transaction without metadata - So, safe and desired change as such.

However, this error should never happen, as this is mainly a programming error (e.g., passing nil to proto.Marshal.

manish-sethi · 2020-07-16T04:25:25Z

core/ledger/kvledger/txmgmt/pvtstatepurgemgmt/purge_mgr.go

@@ -78,7 +78,9 @@ func (p *PurgeMgr) UpdateExpiryInfoOfPvtDataOfOldBlocks(pvtUpdates *privacyenabl
 	builder := newExpiryScheduleBuilder(p.btlPolicy)
 	pvtUpdateCompositeKeyMap := pvtUpdates.ToCompositeKeyMap()
 	for k, vv := range pvtUpdateCompositeKeyMap {
-		builder.add(k.Namespace, k.CollectionName, k.Key, util.ComputeStringHash(k.Key), vv)
+		if err := builder.add(k.Namespace, k.CollectionName, k.Key, util.ComputeStringHash(k.Key), vv); err != nil {


I guess that you mistakenly linked this function to the regular commit path. This function is for old missing pvt data which is in the reconciliation path and does cause a panic but rather retries.

manish-sethi · 2020-07-16T04:31:10Z

core/ledger/kvledger/txmgmt/validation/validator.go

@@ -228,7 +234,9 @@ func (v *validator) validateRangeQuery(ns string, rangeQueryInfo *kvrwset.RangeQ
 		logger.Debug(`Hashing results are not present in the range query info hence, initiating raw KVReads based validation`)
 		qv = &rangeQueryResultsValidator{}
 	}
-	qv.init(rangeQueryInfo, combinedItr)
+	if err := qv.init(rangeQueryInfo, combinedItr); err != nil {


To summarize it in simple terms, this does not change the current behavior but rather returns the error early on.

Signed-off-by: senthil <[email protected]>

fix missing err check in the block commit path

ae271e6

Signed-off-by: senthil <[email protected]>

cendhu force-pushed the ledger-missing-err-check branch from 1ae54cf to ae271e6 Compare July 15, 2020 13:43

cendhu marked this pull request as ready for review July 15, 2020 14:09

cendhu requested a review from a team as a code owner July 15, 2020 14:09

cendhu commented Jul 15, 2020

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manish-sethi approved these changes Jul 16, 2020

View reviewed changes

manish-sethi merged commit 329c858 into hyperledger:master Jul 16, 2020

cendhu added a commit to cendhu/fabric that referenced this pull request Sep 8, 2020

fix missing err check in the block commit path (hyperledger#1543)

734e713

Signed-off-by: senthil <[email protected]>

cendhu mentioned this pull request Sep 9, 2020

fix missing err check in the block commit path [1] #1859

Merged

mastersingh24 pushed a commit that referenced this pull request Sep 9, 2020

fix missing err check in the block commit path (#1543)

09764d8

Signed-off-by: senthil <[email protected]>

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fix missing err check in the commit path #1543

fix missing err check in the commit path #1543

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fix missing err check in the commit path #1543

fix missing err check in the commit path #1543

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cendhu commented Jul 7, 2020

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manish-sethi commented Jul 16, 2020

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