avoid race condition in MakeAffine/ValidatePairing #59
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kevincharm
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kevincharm
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pairing/bn254/suite.go
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| // 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() | ||
| p2.Clone().(*pointG2).g.MakeAffine() | ||
| inv2.Clone().(*pointG2).g.MakeAffine() | ||
| return s.Pair(p1, p2).Equal(s.Pair(inv1, inv2)) |
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I don't think Clone() works like that, it returns a clone of the point, no?
You should be creating local variables if you want to use Clone.
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🤦♂️ indeed you are right. I got mixed up with MakeAffine modifying the point itself...
| g.x.Set(t) | ||
| g.z.SetOne() | ||
| g.t.SetOne() | ||
| c.Set(g) |
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Because of this Set here, I don't think using a Cloned g actually changes much, except it makes the timing of a race more difficult to "hit" in prod/tests...
This function should definitively have a "not safe for concurrent use" in the comment.
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Yeah this bit is dicey. I added the "not safe for concurrent use" warning above the function.
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| @@ -132,10 +132,13 @@ func (s *Suite) Pair(p1 kyber.Point, p2 kyber.Point) kyber.Point { | |||
| return s.GT().Point().(*pointGT).Pair(p1, p2) | |||
| } | |||
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| // NB: Not safe for concurrent calls | |||
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I'm not 100% sure this is actually true since now you clone the inputs 🤔
Addressing issues found in drand/drand#1304 (comment)