x/crypto/sha3: TestKeccakKats failing on freebsd-amd64-race due to invalid unsafe pointer conversion

[bcmills]

From the freebsd-amd64-race builder (https://build.golang.org/log/dbfde792a0d9d30fa34b24190b0023988ef2e63d):

--- FAIL: TestKeccakKats (1.95s)
panic: runtime error: unsafe pointer conversion [recovered]
	panic: runtime error: unsafe pointer conversion

goroutine 20 [running]:
testing.tRunner.func1(0xc0000ba100)
	/tmp/workdir/go/src/testing/testing.go:881 +0x69f
panic(0x6473e0, 0xc00009aac0)
	/tmp/workdir/go/src/runtime/panic.go:915 +0x370
golang.org/x/crypto/sha3.xorInUnaligned(0xc000104a80, 0xc000104b69, 0x90, 0xa8)
	/tmp/workdir/gopath/src/golang.org/x/crypto/sha3/xor_unaligned.go:13 +0x60
golang.org/x/crypto/sha3.(*state).permute(0xc000104a80)
	/tmp/workdir/gopath/src/golang.org/x/crypto/sha3/sha3.go:84 +0x1d3
golang.org/x/crypto/sha3.(*state).padAndPermute(0xc000104a80, 0xc000036706)
	/tmp/workdir/gopath/src/golang.org/x/crypto/sha3/sha3.go:117 +0x347
golang.org/x/crypto/sha3.(*state).Read(0xc000104a80, 0xc0000d45c0, 0x1c, 0x1c, 0x453700, 0xc0000818d0, 0x8)
	/tmp/workdir/gopath/src/golang.org/x/crypto/sha3/sha3.go:163 +0x2e0
golang.org/x/crypto/sha3.(*state).Sum(0xc0001048c0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
	/tmp/workdir/gopath/src/golang.org/x/crypto/sha3/sha3.go:190 +0x233
golang.org/x/crypto/sha3.TestKeccakKats.func1(0x661d91, 0x9)
	/tmp/workdir/gopath/src/golang.org/x/crypto/sha3/sha3_test.go:116 +0x5a9
golang.org/x/crypto/sha3.testUnalignedAndGeneric(0xc0000ba100, 0xc00008df00)
	/tmp/workdir/gopath/src/golang.org/x/crypto/sha3/sha3_test.go:84 +0x14f
golang.org/x/crypto/sha3.TestKeccakKats(0xc0000ba100)
	/tmp/workdir/gopath/src/golang.org/x/crypto/sha3/sha3_test.go:93 +0x5c
testing.tRunner(0xc0000ba100, 0x66bd20)
	/tmp/workdir/go/src/testing/testing.go:916 +0x1a9
created by testing.(*T).Run
	/tmp/workdir/go/src/testing/testing.go:967 +0x652
FAIL	golang.org/x/crypto/sha3	1.966s

CC @FiloSottile @mknyszek

[bcmills]

Looks like the wild reads there are conditional, and the punned slice type is of uint64 so the collector won't try to chase pointers through it.

I'm not sure whether that's actually unsafe in practice, but it does potentially produce an out-of-object slice.

[gopherbot]

Change https://golang.org/cl/203837 mentions this issue: sha3: align (*state).storage