[cipherstash-agent]

Requested by CipherStash · project thread

Summary

Fixes CIP-5160 (G1, G2). A failed hand-off to the guest no longer leaves a token or ZeroKMS response in guest memory, and stashgen releases its engine.

Changes

• place (encrypt) and placeAuth (auth) were duplicates. They are replaced by one guest.Place in internal/guest.
• On any failure after se_alloc, Place zeroes the bytes it wrote and clears the pointer slot, so a half-written out-slot pair cannot leave a dangling pointer.
• It does not call se_dealloc. The guest ABI docs allow a host import to re-enter only through se_alloc, so the issue's suggested fix would violate them. The zeroed buffer is freed by the guest registry at shutdown.
• stashgen's run now closes the engine it was given when it implements io.Closer, on every return path.

Verification

• go build, go vet and go test pass for internal/guest, auth, encrypt, cmd/stashgen, and stashgen.
• New tests fail without the fix and pass with it: buffer wiped and pointer slot cleared when either out-slot write fails, empty value placed, engine closed on success and on refusal.

Related

• Linear CIP-5160.
• No changeset: the Go module is released by hand, not through Changesets. No skill is affected.

Review notes

/code-review medium raised the se_dealloc re-entry, a stale pointer slot, and wrapper/test placement. These were fixed. It also suggested the caller should own the engine's lifetime; I kept run closing it and documented that on run.

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Latest commit: c832493

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