clone point to avoid race condition in MakeAffine

drand · Apr 3, 2024 · 19712af · 19712af
1 parent 54d4f93
commit 19712af
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Showing 2 changed files with 15 additions and 12 deletions.
diff --git a/pairing/bn254/suite.go b/pairing/bn254/suite.go
@@ -132,6 +132,7 @@ func (s *Suite) Pair(p1 kyber.Point, p2 kyber.Point) kyber.Point {
 	return s.GT().Point().(*pointGT).Pair(p1, p2)
 }
 
+// NB: Not safe for concurrent calls
 func (s *Suite) ValidatePairing(p1, p2, inv1, inv2 kyber.Point) bool {
 	p2.(*pointG2).g.MakeAffine()
 	inv2.(*pointG2).g.MakeAffine()

diff --git a/pairing/bn254/twist.go b/pairing/bn254/twist.go
@@ -178,23 +178,25 @@ func (c *twistPoint) Mul(a *twistPoint, scalar *big.Int) {
 }
 
 func (c *twistPoint) MakeAffine() {
-	if c.z.IsOne() {
+	res := c.Clone()
+	if res.z.IsOne() {
 		return
-	} else if c.z.IsZero() {
-		c.x.SetZero()
-		c.y.SetOne()
-		c.t.SetZero()
+	} else if res.z.IsZero() {
+		res.x.SetZero()
+		res.y.SetOne()
+		res.t.SetZero()
 		return
 	}
 
-	zInv := (&gfP2{}).Invert(&c.z)
-	t := (&gfP2{}).Mul(&c.y, zInv)
+	zInv := (&gfP2{}).Invert(&res.z)
+	t := (&gfP2{}).Mul(&res.y, zInv)
 	zInv2 := (&gfP2{}).Square(zInv)
-	c.y.Mul(t, zInv2)
-	t.Mul(&c.x, zInv2)
-	c.x.Set(t)
-	c.z.SetOne()
-	c.t.SetOne()
+	res.y.Mul(t, zInv2)
+	t.Mul(&res.x, zInv2)
+	res.x.Set(t)
+	res.z.SetOne()
+	res.t.SetOne()
+	c.Set(res)
 }
 
 func (c *twistPoint) Neg(a *twistPoint) {