sstable: avoid overflow in GetScaledProperties

Author: RaduBerinde

sstable/properties.go

@@ -17,6 +17,7 @@ import (
 	"strings"
 	"unsafe"
 
+	"github.com/cockroachdb/crlib/crmath"
 	"github.com/cockroachdb/pebble/internal/intern"
 	"github.com/cockroachdb/pebble/internal/invariants"
 	"github.com/cockroachdb/pebble/sstable/colblk"
@@ -143,7 +144,7 @@ func (c *CommonProperties) GetScaledProperties(backingSize, size uint64) CommonP
 	backingSize = max(backingSize, size)
 
 	scale := func(a uint64) uint64 {
-		return (a*size + backingSize - 1) / backingSize
+		return crmath.ScaleUint64(a, size, backingSize)
 	}
 	// It's important that no non-zero fields (like NumDeletions, NumRangeKeySets)
 	// become zero (or vice-versa).

sstable/properties_test.go

@@ -138,12 +138,10 @@ func TestPropertiesSave(t *testing.T) {
 func TestScalePropertiesBadSizes(t *testing.T) {
 	// Verify that GetScaledProperties works even if the given sizes are not
 	// valid.
-	p := Properties{
-		CommonProperties: CommonProperties{
-			NumDeletions:  0,
-			NumEntries:    1,
-			NumDataBlocks: 10,
-		},
+	p := CommonProperties{
+		NumDeletions:  0,
+		NumEntries:    1,
+		NumDataBlocks: 10,
 	}
 	scaled := p.GetScaledProperties(100, 0)
 	require.Equal(t, uint64(0), scaled.NumDeletions)
@@ -156,6 +154,23 @@ func TestScalePropertiesBadSizes(t *testing.T) {
 	require.Equal(t, uint64(10), scaled.NumDataBlocks)
 }
 
+func TestScalePropertiesOverflow(t *testing.T) {
+	// Verify that GetScaledProperties works even if the given sizes are not
+	// valid.
+	p := CommonProperties{
+		RawKeySize:   1 << 40,
+		RawValueSize: 1 << 50,
+	}
+	scaled := p.GetScaledProperties(1<<60, 1<<60)
+	require.Equal(t, p, scaled)
+
+	scaled = p.GetScaledProperties(1<<60, 1<<50)
+	require.Equal(t, scaled, CommonProperties{
+		RawKeySize:   1 << 30,
+		RawValueSize: 1 << 40,
+	})
+}
+
 func BenchmarkPropertiesLoad(b *testing.B) {
 	var w rowblk.Writer
 	w.RestartInterval = propertiesBlockRestartInterval