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fix: temporary workaround for gnark-crypto AVX-512 innerProdVec SIGSEGV #3130

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fix: temporary workaround for gnark-crypto AVX-512 innerProdVec SIGSEGV #3130

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9 changes: 9 additions & 0 deletions prover/circuits/pi-interconnection/keccak/prover/maths/common/vector/vector.go
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,15 @@ func ScalarMul(res, vec []field.Element, scalar field.Element) {
func ScalarProd(a, b []field.Element) field.Element {
// The length checks is done by gnark-crypto already
a_ := fr.Vector(a)
// Workaround for gnark-crypto AVX-512 innerProdVec overread:
// The assembly reads 4 bytes past the last element of the receiver via
// VPMULUDQ.BCST at offset 28 (8-byte load from byte 28 of a 32-byte element).
// When the allocation is page-aligned this causes SIGSEGV. Ensure extra capacity.
if len(a) > 0 && cap(a) == len(a) {
padded := make(fr.Vector, len(a)+1)
copy(padded, a_)
a_ = padded[:len(a)]
}
res := a_.InnerProduct(fr.Vector(b))
return res
}
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4 changes: 3 additions & 1 deletion prover/circuits/pi-interconnection/keccak/prover/maths/field/gen.go
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Expand Up @@ -16,7 +16,9 @@ func ParBatchInvert(a []Element, numCPU int) []Element {
numCPU = runtime.NumCPU()
}

res := make([]Element, len(a))
// Allocate with +1 capacity to prevent gnark-crypto AVX-512 innerProdVec
// overread when the result is subsequently used in InnerProduct.
res := make([]Element, len(a), len(a)+1)

parallel.Execute(len(a), func(start, stop int) {
subRes := BatchInvert(a[start:stop])
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