Fix block boundary checking in FetchBlockRegion(s)

database/ffldb/blockio.go

@@ -56,6 +56,11 @@ const (
 	//  [4:8]  File offset (4 bytes)
 	//  [8:12] Block length (4 bytes)
 	blockLocSize = 12
+
+	// blockMetadataSize is the number of bytes added as the metadata to
+	// a serialized block (4 bytes network version + 4 bytes block size +
+	// 4 bytes checksum).
+	blockMetadataSize = 12
 )
 
 var (

database/ffldb/db.go

@@ -1455,12 +1455,15 @@ func (tx *transaction) FetchBlockRegion(region *database.BlockRegion) ([]byte, e
 	}
 	location := deserializeBlockLoc(blockRow)
 
+	// Calculate the actual block size by removing the metadata.
+	blockLen := location.blockLen - blockMetadataSize
+
 	// Ensure the region is within the bounds of the block.
 	endOffset := region.Offset + region.Len
-	if endOffset < region.Offset || endOffset > location.blockLen {
+	if endOffset < region.Offset || endOffset > blockLen {
 		str := fmt.Sprintf("block %s region offset %d, length %d "+
 			"exceeds block length of %d", region.Hash,
-			region.Offset, region.Len, location.blockLen)
+			region.Offset, region.Len, blockLen)
 		return nil, makeDbErr(database.ErrBlockRegionInvalid, str, nil)
 
 	}
@@ -1553,12 +1556,15 @@ func (tx *transaction) FetchBlockRegions(regions []database.BlockRegion) ([][]by
 		}
 		location := deserializeBlockLoc(blockRow)
 
+		// Calculate the actual block size by removing the metadata.
+		blockLen := location.blockLen - blockMetadataSize
+
 		// Ensure the region is within the bounds of the block.
 		endOffset := region.Offset + region.Len
-		if endOffset < region.Offset || endOffset > location.blockLen {
+		if endOffset < region.Offset || endOffset > blockLen {
 			str := fmt.Sprintf("block %s region offset %d, length "+
 				"%d exceeds block length of %d", region.Hash,
-				region.Offset, region.Len, location.blockLen)
+				region.Offset, region.Len, blockLen)
 			return nil, makeDbErr(database.ErrBlockRegionInvalid, str, nil)
 		}
 

database/ffldb/interface_test.go

@@ -1360,6 +1360,19 @@ func testFetchBlockIO(tc *testContext, tx database.Tx) bool {
 		if !checkDbError(tc.t, testName, err, wantErrCode) {
 			return false
 		}
+
+		// Ensure fetching a block region larger than the block returns
+		// the expected error.
+		testName = fmt.Sprintf("FetchBlockRegion(%s) out of block size",
+			blockHash)
+		wantErrCode = database.ErrBlockRegionInvalid
+		region.Hash = blockHash
+		region.Offset = 0
+		region.Len = uint32(len(blockBytes) + 1)
+		_, err = tx.FetchBlockRegion(&region)
+		if !checkDbError(tc.t, testName, err, wantErrCode) {
+			return false
+		}
 	}
 
 	// -----------------
@@ -1500,6 +1513,20 @@ func testFetchBlockIO(tc *testContext, tx database.Tx) bool {
 	}
 	wantErrCode = database.ErrBlockRegionInvalid
 	_, err = tx.FetchBlockRegions(badBlockRegions)
+	if !checkDbError(tc.t, testName, err, wantErrCode) {
+		return false
+	}
+
+	// Ensure fetching block regions larger than the block returns the
+	// expected error.
+	testName = "FetchBlockRegions out of bunds"
+	badBlockRegions = badBlockRegions[:len(badBlockRegions)-1]
+	for i := range badBlockRegions {
+		badBlockRegions[i].Offset = 0
+		badBlockRegions[i].Len = uint32(len(allBlockBytes[i]) + 1)
+	}
+	wantErrCode = database.ErrBlockRegionInvalid
+	_, err = tx.FetchBlockRegions(badBlockRegions)
 	return checkDbError(tc.t, testName, err, wantErrCode)
 }