From 8dc6efca2009ff50b8f9aab07e38b88a12da8a2b Mon Sep 17 00:00:00 2001
From: Chris Duncan <chris@zoso.dev>
Date: Sat, 29 Aug 2026 01:53:51 -0700
Subject: [PATCH] Throw if memory grows instead of just rewrapping it.

---
 src/lib/derive.ts |  8 +++++---
 src/lib/sign.ts   |  8 +++++---
 src/lib/verify.ts | 10 ++++++----
 src/lib/wasm.ts   |  3 ++-
 4 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/src/lib/derive.ts b/src/lib/derive.ts
index 30f01ad..338f7cc 100644
--- a/src/lib/derive.ts
+++ b/src/lib/derive.ts
@@ -1,7 +1,7 @@
 //! SPDX-FileCopyrightText: 2026 Chris Duncan <chris@codecow.com>
 //! SPDX-License-Identifier: GPL-3.0-or-later
 
-import { Mutex, Pointers, clear, constants, exports, isBytes, normalize } from './wasm'
+import { Mutex, Nano25519TypeError, Pointers, clearMemory, constants, exports, isBytes, normalize } from './wasm'
 
 const { KEY_BYTELENGTH, } = constants
 
@@ -18,7 +18,9 @@ export function derive (prv: unknown, out?: unknown): string | Uint8Array<ArrayB
 			buffer[Pointers.INPUT_PRV + i] = privateKey[i]
 		}
 		exports.derive()
-		buffer = new Uint8Array(exports.memory.buffer)
+		if (exports.memory.buffer !== buffer.buffer) {
+			throw new Nano25519TypeError('WASM memory buffer detached')
+		}
 		for (let i = 0; i < KEY_BYTELENGTH; i++) {
 			publicKey[i] = buffer[Pointers.OUTPUT_DERIVE + i]
 		}
@@ -37,6 +39,6 @@ export function derive (prv: unknown, out?: unknown): string | Uint8Array<ArrayB
 		}
 	} finally {
 		privateKey.fill(0)
-		clear(buffer)
+		clearMemory()
 	}
 }
diff --git a/src/lib/sign.ts b/src/lib/sign.ts
index fe50570..bd71a4e 100644
--- a/src/lib/sign.ts
+++ b/src/lib/sign.ts
@@ -1,7 +1,7 @@
 //! SPDX-FileCopyrightText: 2026 Chris Duncan <chris@codecow.com>
 //! SPDX-License-Identifier: GPL-3.0-or-later
 
-import { Mutex, Pointers, clear, constants, exports, isBytes, normalize } from './wasm'
+import { Mutex, Nano25519TypeError, Pointers, clearMemory, constants, exports, isBytes, normalize } from './wasm'
 
 const { KEY_BYTELENGTH, MAX_MESSAGE_BYTELENGTH, SIGNATURE_BYTELENGTH, } = constants
 
@@ -26,7 +26,9 @@ export function sign (msg: unknown, prv: unknown, pub: unknown, out?: unknown):
 			buffer[Pointers.INPUT_PUB + i] = publicKey[i]
 		}
 		exports.sign(message.byteLength)
-		buffer = new Uint8Array(exports.memory.buffer)
+		if (exports.memory.buffer !== buffer.buffer) {
+			throw new Nano25519TypeError('WASM memory buffer detached')
+		}
 		for (let i = 0; i < SIGNATURE_BYTELENGTH; i++) {
 			signature[i] = buffer[Pointers.OUTPUT_SIGN + i]
 		}
@@ -46,6 +48,6 @@ export function sign (msg: unknown, prv: unknown, pub: unknown, out?: unknown):
 	} finally {
 		privateKey.fill(0)
 		publicKey.fill(0)
-		clear(buffer)
+		clearMemory()
 	}
 }
diff --git a/src/lib/verify.ts b/src/lib/verify.ts
index 2b2ae1e..f9124bf 100644
--- a/src/lib/verify.ts
+++ b/src/lib/verify.ts
@@ -1,7 +1,7 @@
 //! SPDX-FileCopyrightText: 2026 Chris Duncan <chris@codecow.com>
 //! SPDX-License-Identifier: GPL-3.0-or-later
 
-import { Mutex, Pointers, clear, constants, exports, normalize, } from './wasm'
+import { Mutex, Nano25519TypeError, Pointers, clearMemory, constants, exports, normalize, } from './wasm'
 
 const { BLOCKHASH_BYTELENGTH, KEY_BYTELENGTH, MAX_MESSAGE_BYTELENGTH, MAX_VERIFY_BLOCKS, SIGNATURE_BYTELENGTH, } = constants
 
@@ -26,7 +26,7 @@ export function verify (sig: unknown, msg: unknown, pub: unknown): boolean {
 		const verified = buffer[Pointers.OUTPUT_VERIFY]
 		return verified === 0
 	} finally {
-		clear(buffer)
+		clearMemory()
 	}
 }
 
@@ -70,12 +70,14 @@ export function verify_blocks (pub: unknown, data: unknown): boolean[] {
 			p += BLOCKHASH_BYTELENGTH
 		}
 		exports.verify_blocks(count)
-		buffer = new Uint8Array(exports.memory.buffer)
+		if (exports.memory.buffer !== buffer.buffer) {
+			throw new Nano25519TypeError('WASM memory buffer detached')
+		}
 		for (let i = 0; i < count; i++) {
 			verified[i] = buffer[Pointers.OUTPUT_VERIFY + i]
 		}
 		return [...verified].map(v => v === 0)
 	} finally {
-		clear(buffer)
+		clearMemory()
 	}
 }
diff --git a/src/lib/wasm.ts b/src/lib/wasm.ts
index 6640700..61e332a 100644
--- a/src/lib/wasm.ts
+++ b/src/lib/wasm.ts
@@ -103,7 +103,8 @@ export class Pointers {
 	static get OUTPUT_VERIFY (): number { return this.#get(OUTPUT_VERIFY) }
 }
 
-export function clear (memory: Uint8Array): void {
+export function clearMemory (): void {
+	const memory = new Uint8Array(exports.memory.buffer)
 	memory.fill(0, INPUT_MSG, INPUT_MSG + MAX_MESSAGE_BYTELENGTH)
 	memory.fill(0, INPUT_PRV, INPUT_PRV + KEY_BYTELENGTH)
 	memory.fill(0, INPUT_PUB, INPUT_PUB + KEY_BYTELENGTH)
-- 
2.52.0