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authorPéter Szilágyi <peterke@gmail.com>2017-06-28 18:12:13 +0800
committerGitHub <noreply@github.com>2017-06-28 18:12:13 +0800
commitdfd076244dd0c2d809f9dd0080feab167ba9560c (patch)
tree5791af8e261c51e0ebde666a0a6086921d27279c /core/vm
parent6dc32e897a0e71982adbbf7123e19115f27f7135 (diff)
parente4301564c2af0b4f084a3bcf8ddcec5e84ac4ead (diff)
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Merge pull request #14718 from holiman/gascalc_fix
core/vm: fix overflow in gas calculation formula
Diffstat (limited to 'core/vm')
-rw-r--r--core/vm/gas_table.go16
-rw-r--r--core/vm/gas_table_test.go18
2 files changed, 17 insertions, 17 deletions
diff --git a/core/vm/gas_table.go b/core/vm/gas_table.go
index 24ad6caa5..761ca4450 100644
--- a/core/vm/gas_table.go
+++ b/core/vm/gas_table.go
@@ -17,7 +17,6 @@
package vm
import (
- gmath "math"
"math/big"
"github.com/ethereum/go-ethereum/common"
@@ -28,15 +27,20 @@ import (
// memoryGasCosts calculates the quadratic gas for memory expansion. It does so
// only for the memory region that is expanded, not the total memory.
func memoryGasCost(mem *Memory, newMemSize uint64) (uint64, error) {
- // The maximum that will fit in a uint64 is max_word_count - 1
- // anything above that will result in an overflow.
- if newMemSize > gmath.MaxUint64-32 {
- return 0, errGasUintOverflow
- }
if newMemSize == 0 {
return 0, nil
}
+ // The maximum that will fit in a uint64 is max_word_count - 1
+ // anything above that will result in an overflow.
+ // Additionally, a newMemSize which results in a
+ // newMemSizeWords larger than 0x7ffffffff will cause the square operation
+ // to overflow.
+ // The constant 0xffffffffe0 is the highest number that can be used without
+ // overflowing the gas calculation
+ if newMemSize > 0xffffffffe0 {
+ return 0, errGasUintOverflow
+ }
newMemSizeWords := toWordSize(newMemSize)
newMemSize = newMemSizeWords * 32
diff --git a/core/vm/gas_table_test.go b/core/vm/gas_table_test.go
index 1ee909e92..1b91aee56 100644
--- a/core/vm/gas_table_test.go
+++ b/core/vm/gas_table_test.go
@@ -16,24 +16,20 @@
package vm
-import (
- "math"
- "testing"
-)
+import "testing"
func TestMemoryGasCost(t *testing.T) {
- size := uint64(math.MaxUint64 - 64)
- _, err := memoryGasCost(&Memory{}, size)
+ //size := uint64(math.MaxUint64 - 64)
+ size := uint64(0xffffffffe0)
+ v, err := memoryGasCost(&Memory{}, size)
if err != nil {
t.Error("didn't expect error:", err)
}
-
- _, err = memoryGasCost(&Memory{}, size+32)
- if err != nil {
- t.Error("didn't expect error:", err)
+ if v != 36028899963961341 {
+ t.Errorf("Expected: 36028899963961341, got %d", v)
}
- _, err = memoryGasCost(&Memory{}, size+33)
+ _, err = memoryGasCost(&Memory{}, size+1)
if err == nil {
t.Error("expected error")
}