From 50b2d29ff37cc193698963fc9e4da470b7218815 Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Fri, 13 Nov 2020 09:27:57 +0100
Subject: [PATCH] crypto/bn256: improve bn256 fuzzer (#21815)
* crypto/cloudflare: fix nil deref in random G1/G2 reading
* crypto/bn256: improve fuzzer
* crypto/bn256: fix some flaws in fuzzer
---
crypto/bn256/bn256_fuzz.go | 117 ++++++++++++++-----------------
crypto/bn256/cloudflare/bn256.go | 2 +-
2 files changed, 53 insertions(+), 66 deletions(-)
diff --git a/crypto/bn256/bn256_fuzz.go b/crypto/bn256/bn256_fuzz.go
index 733d7ce27f..29fe7aab84 100644
--- a/crypto/bn256/bn256_fuzz.go
+++ b/crypto/bn256/bn256_fuzz.go
@@ -8,42 +8,52 @@ package bn256
import (
"bytes"
+ "fmt"
+ "io"
"math/big"
cloudflare "github.com/ledgerwatch/turbo-geth/crypto/bn256/cloudflare"
google "github.com/ledgerwatch/turbo-geth/crypto/bn256/google"
)
-// FuzzAdd fuzzez bn256 addition between the Google and Cloudflare libraries.
-func FuzzAdd(data []byte) int {
- // Ensure we have enough data in the first place
- if len(data) != 128 {
- return 0
+func getG1Points(input io.Reader) (*cloudflare.G1, *google.G1) {
+ _, xc, err := cloudflare.RandomG1(input)
+ if err != nil {
+ // insufficient input
+ return nil, nil
}
- // Ensure both libs can parse the first curve point
- xc := new(cloudflare.G1)
- _, errc := xc.Unmarshal(data[:64])
-
xg := new(google.G1)
- _, errg := xg.Unmarshal(data[:64])
-
- if (errc == nil) != (errg == nil) {
- panic("parse mismatch")
- } else if errc != nil {
- return 0
+ if _, err := xg.Unmarshal(xc.Marshal()); err != nil {
+ panic(fmt.Sprintf("Could not marshal cloudflare -> google:", err))
}
- // Ensure both libs can parse the second curve point
- yc := new(cloudflare.G1)
- _, errc = yc.Unmarshal(data[64:])
+ return xc, xg
+}
- yg := new(google.G1)
- _, errg = yg.Unmarshal(data[64:])
+func getG2Points(input io.Reader) (*cloudflare.G2, *google.G2) {
+ _, xc, err := cloudflare.RandomG2(input)
+ if err != nil {
+ // insufficient input
+ return nil, nil
+ }
+ xg := new(google.G2)
+ if _, err := xg.Unmarshal(xc.Marshal()); err != nil {
+ panic(fmt.Sprintf("Could not marshal cloudflare -> google:", err))
+ }
+ return xc, xg
+}
- if (errc == nil) != (errg == nil) {
- panic("parse mismatch")
- } else if errc != nil {
+// FuzzAdd fuzzez bn256 addition between the Google and Cloudflare libraries.
+func FuzzAdd(data []byte) int {
+ input := bytes.NewReader(data)
+ xc, xg := getG1Points(input)
+ if xc == nil {
return 0
}
+ yc, yg := getG1Points(input)
+ if yc == nil {
+ return 0
+ }
+ // Ensure both libs can parse the second curve point
// Add the two points and ensure they result in the same output
rc := new(cloudflare.G1)
rc.Add(xc, yc)
@@ -54,73 +64,50 @@ func FuzzAdd(data []byte) int {
if !bytes.Equal(rc.Marshal(), rg.Marshal()) {
panic("add mismatch")
}
- return 0
+ return 1
}
// FuzzMul fuzzez bn256 scalar multiplication between the Google and Cloudflare
// libraries.
func FuzzMul(data []byte) int {
- // Ensure we have enough data in the first place
- if len(data) != 96 {
+ input := bytes.NewReader(data)
+ pc, pg := getG1Points(input)
+ if pc == nil {
return 0
}
- // Ensure both libs can parse the curve point
- pc := new(cloudflare.G1)
- _, errc := pc.Unmarshal(data[:64])
-
- pg := new(google.G1)
- _, errg := pg.Unmarshal(data[:64])
-
- if (errc == nil) != (errg == nil) {
- panic("parse mismatch")
- } else if errc != nil {
+ // Add the two points and ensure they result in the same output
+ remaining := input.Len()
+ if remaining == 0 {
return 0
}
- // Add the two points and ensure they result in the same output
+ buf := make([]byte, remaining)
+ input.Read(buf)
+
rc := new(cloudflare.G1)
- rc.ScalarMult(pc, new(big.Int).SetBytes(data[64:]))
+ rc.ScalarMult(pc, new(big.Int).SetBytes(buf))
rg := new(google.G1)
- rg.ScalarMult(pg, new(big.Int).SetBytes(data[64:]))
+ rg.ScalarMult(pg, new(big.Int).SetBytes(buf))
if !bytes.Equal(rc.Marshal(), rg.Marshal()) {
panic("scalar mul mismatch")
}
- return 0
+ return 1
}
func FuzzPair(data []byte) int {
- // Ensure we have enough data in the first place
- if len(data) != 192 {
+ input := bytes.NewReader(data)
+ pc, pg := getG1Points(input)
+ if pc == nil {
return 0
}
- // Ensure both libs can parse the curve point
- pc := new(cloudflare.G1)
- _, errc := pc.Unmarshal(data[:64])
-
- pg := new(google.G1)
- _, errg := pg.Unmarshal(data[:64])
-
- if (errc == nil) != (errg == nil) {
- panic("parse mismatch")
- } else if errc != nil {
- return 0
- }
- // Ensure both libs can parse the twist point
- tc := new(cloudflare.G2)
- _, errc = tc.Unmarshal(data[64:])
-
- tg := new(google.G2)
- _, errg = tg.Unmarshal(data[64:])
-
- if (errc == nil) != (errg == nil) {
- panic("parse mismatch")
- } else if errc != nil {
+ tc, tg := getG2Points(input)
+ if tc == nil {
return 0
}
// Pair the two points and ensure thet result in the same output
if cloudflare.PairingCheck([]*cloudflare.G1{pc}, []*cloudflare.G2{tc}) != google.PairingCheck([]*google.G1{pg}, []*google.G2{tg}) {
panic("pair mismatch")
}
- return 0
+ return 1
}
diff --git a/crypto/bn256/cloudflare/bn256.go b/crypto/bn256/cloudflare/bn256.go
index 38822a76bf..a6dd972ba8 100644
--- a/crypto/bn256/cloudflare/bn256.go
+++ b/crypto/bn256/cloudflare/bn256.go
@@ -23,7 +23,7 @@ import (
func randomK(r io.Reader) (k *big.Int, err error) {
for {
k, err = rand.Int(r, Order)
- if k.Sign() > 0 || err != nil {
+ if err != nil || k.Sign() > 0 {
return
}
}
--
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