fix: bounds check

Author: steveluscher

packages/library-legacy/src/message/legacy.ts

@@ -16,6 +16,7 @@ import {
 import {TransactionInstruction} from '../transaction';
 import {CompiledKeys} from './compiled-keys';
 import {MessageAccountKeys} from './account-keys';
+import {guardedShift, guardedSplice} from '../utils/guarded-array-utils';
 
 /**
  * An instruction to execute by a program
@@ -268,7 +269,7 @@ export class Message {
     // Slice up wire data
     let byteArray = [...buffer];
 
-    const numRequiredSignatures = byteArray.shift()!;
+    const numRequiredSignatures = guardedShift(byteArray);
     if (
       numRequiredSignatures !==
       (numRequiredSignatures & VERSION_PREFIX_MASK)
@@ -278,26 +279,26 @@ export class Message {
       );
     }
 
-    const numReadonlySignedAccounts = byteArray.shift()!;
-    const numReadonlyUnsignedAccounts = byteArray.shift()!;
+    const numReadonlySignedAccounts = guardedShift(byteArray);
+    const numReadonlyUnsignedAccounts = guardedShift(byteArray);
 
     const accountCount = shortvec.decodeLength(byteArray);
     let accountKeys = [];
     for (let i = 0; i < accountCount; i++) {
-      const account = byteArray.splice(0, PUBLIC_KEY_LENGTH);
+      const account = guardedSplice(byteArray, 0, PUBLIC_KEY_LENGTH);
       accountKeys.push(new PublicKey(Buffer.from(account)));
     }
 
-    const recentBlockhash = byteArray.splice(0, PUBLIC_KEY_LENGTH);
+    const recentBlockhash = guardedSplice(byteArray, 0, PUBLIC_KEY_LENGTH);
 
     const instructionCount = shortvec.decodeLength(byteArray);
     let instructions: CompiledInstruction[] = [];
     for (let i = 0; i < instructionCount; i++) {
-      const programIdIndex = byteArray.shift()!;
+      const programIdIndex = guardedShift(byteArray);
       const accountCount = shortvec.decodeLength(byteArray);
-      const accounts = byteArray.splice(0, accountCount);
+      const accounts = guardedSplice(byteArray, 0, accountCount);
       const dataLength = shortvec.decodeLength(byteArray);
-      const dataSlice = byteArray.splice(0, dataLength);
+      const dataSlice = guardedSplice(byteArray, 0, dataLength);
       const data = bs58.encode(Buffer.from(dataSlice));
       instructions.push({
         programIdIndex,

packages/library-legacy/src/message/v0.ts

@@ -16,6 +16,7 @@ import {TransactionInstruction} from '../transaction';
 import {AddressLookupTableAccount} from '../programs';
 import {CompiledKeys} from './compiled-keys';
 import {AccountKeysFromLookups, MessageAccountKeys} from './account-keys';
+import {guardedShift, guardedSplice} from '../utils/guarded-array-utils';
 
 /**
  * Message constructor arguments
@@ -426,7 +427,7 @@ export class MessageV0 {
   static deserialize(serializedMessage: Uint8Array): MessageV0 {
     let byteArray = [...serializedMessage];
 
-    const prefix = byteArray.shift() as number;
+    const prefix = guardedShift(byteArray);
     const maskedPrefix = prefix & VERSION_PREFIX_MASK;
     assert(
       prefix !== maskedPrefix,
@@ -440,29 +441,35 @@ export class MessageV0 {
     );
 
     const header: MessageHeader = {
-      numRequiredSignatures: byteArray.shift() as number,
-      numReadonlySignedAccounts: byteArray.shift() as number,
-      numReadonlyUnsignedAccounts: byteArray.shift() as number,
+      numRequiredSignatures: guardedShift(byteArray),
+      numReadonlySignedAccounts: guardedShift(byteArray),
+      numReadonlyUnsignedAccounts: guardedShift(byteArray),
     };
 
     const staticAccountKeys = [];
     const staticAccountKeysLength = shortvec.decodeLength(byteArray);
     for (let i = 0; i < staticAccountKeysLength; i++) {
       staticAccountKeys.push(
-        new PublicKey(byteArray.splice(0, PUBLIC_KEY_LENGTH)),
+        new PublicKey(guardedSplice(byteArray, 0, PUBLIC_KEY_LENGTH)),
       );
     }
 
-    const recentBlockhash = bs58.encode(byteArray.splice(0, PUBLIC_KEY_LENGTH));
+    const recentBlockhash = bs58.encode(
+      guardedSplice(byteArray, 0, PUBLIC_KEY_LENGTH),
+    );
 
     const instructionCount = shortvec.decodeLength(byteArray);
     const compiledInstructions: MessageCompiledInstruction[] = [];
     for (let i = 0; i < instructionCount; i++) {
-      const programIdIndex = byteArray.shift() as number;
+      const programIdIndex = guardedShift(byteArray);
       const accountKeyIndexesLength = shortvec.decodeLength(byteArray);
-      const accountKeyIndexes = byteArray.splice(0, accountKeyIndexesLength);
+      const accountKeyIndexes = guardedSplice(
+        byteArray,
+        0,
+        accountKeyIndexesLength,
+      );
       const dataLength = shortvec.decodeLength(byteArray);
-      const data = new Uint8Array(byteArray.splice(0, dataLength));
+      const data = new Uint8Array(guardedSplice(byteArray, 0, dataLength));
       compiledInstructions.push({
         programIdIndex,
         accountKeyIndexes,
@@ -473,11 +480,21 @@ export class MessageV0 {
     const addressTableLookupsCount = shortvec.decodeLength(byteArray);
     const addressTableLookups: MessageAddressTableLookup[] = [];
     for (let i = 0; i < addressTableLookupsCount; i++) {
-      const accountKey = new PublicKey(byteArray.splice(0, PUBLIC_KEY_LENGTH));
+      const accountKey = new PublicKey(
+        guardedSplice(byteArray, 0, PUBLIC_KEY_LENGTH),
+      );
       const writableIndexesLength = shortvec.decodeLength(byteArray);
-      const writableIndexes = byteArray.splice(0, writableIndexesLength);
+      const writableIndexes = guardedSplice(
+        byteArray,
+        0,
+        writableIndexesLength,
+      );
       const readonlyIndexesLength = shortvec.decodeLength(byteArray);
-      const readonlyIndexes = byteArray.splice(0, readonlyIndexesLength);
+      const readonlyIndexes = guardedSplice(
+        byteArray,
+        0,
+        readonlyIndexesLength,
+      );
       addressTableLookups.push({
         accountKey,
         writableIndexes,

packages/library-legacy/src/transaction/legacy.ts

@@ -12,6 +12,7 @@ import type {Signer} from '../keypair';
 import type {Blockhash} from '../blockhash';
 import type {CompiledInstruction} from '../message';
 import {sign, verify} from '../utils/ed25519';
+import {guardedSplice} from '../utils/guarded-array-utils';
 
 /** @internal */
 type MessageSignednessErrors = {
@@ -904,7 +905,7 @@ export class Transaction {
     const signatureCount = shortvec.decodeLength(byteArray);
     let signatures = [];
     for (let i = 0; i < signatureCount; i++) {
-      const signature = byteArray.splice(0, SIGNATURE_LENGTH_IN_BYTES);
+      const signature = guardedSplice(byteArray, 0, SIGNATURE_LENGTH_IN_BYTES);
       signatures.push(bs58.encode(Buffer.from(signature)));
     }
 

packages/library-legacy/src/transaction/versioned.ts

@@ -8,6 +8,7 @@ import * as shortvec from '../utils/shortvec-encoding';
 import * as Layout from '../layout';
 import {sign} from '../utils/ed25519';
 import {PublicKey} from '../publickey';
+import {guardedSplice} from '../utils/guarded-array-utils';
 
 export type TransactionVersion = 'legacy' | 0;
 
@@ -82,7 +83,7 @@ export class VersionedTransaction {
     const signaturesLength = shortvec.decodeLength(byteArray);
     for (let i = 0; i < signaturesLength; i++) {
       signatures.push(
-        new Uint8Array(byteArray.splice(0, SIGNATURE_LENGTH_IN_BYTES)),
+        new Uint8Array(guardedSplice(byteArray, 0, SIGNATURE_LENGTH_IN_BYTES)),
       );
     }
 

packages/library-legacy/src/utils/guarded-array-utils.ts

@@ -0,0 +1,34 @@
+const END_OF_BUFFER_ERROR_MESSAGE = 'Reached end of buffer unexpectedly';
+
+/**
+ * Delegates to `Array#shift`, but throws if the array is zero-length.
+ */
+export function guardedShift<T>(byteArray: T[]): T {
+  if (byteArray.length === 0) {
+    throw new Error(END_OF_BUFFER_ERROR_MESSAGE);
+  }
+  return byteArray.shift() as T;
+}
+
+/**
+ * Delegates to `Array#splice`, but throws if the section being spliced out extends past the end of
+ * the array.
+ */
+export function guardedSplice<T>(
+  byteArray: T[],
+  ...args:
+    | [start: number, deleteCount?: number]
+    | [start: number, deleteCount: number, ...items: T[]]
+): T[] {
+  const [start] = args;
+  if (
+    args.length === 2 // Implies that `deleteCount` was supplied
+      ? start + (args[1] ?? 0) > byteArray.length
+      : start >= byteArray.length
+  ) {
+    throw new Error(END_OF_BUFFER_ERROR_MESSAGE);
+  }
+  return byteArray.splice(
+    ...(args as Parameters<typeof Array.prototype.splice>),
+  );
+}

packages/library-legacy/src/validator-info.ts

@@ -9,6 +9,7 @@ import {
 import * as Layout from './layout';
 import * as shortvec from './utils/shortvec-encoding';
 import {PublicKey, PUBLIC_KEY_LENGTH} from './publickey';
+import {guardedShift, guardedSplice} from './utils/guarded-array-utils';
 
 export const VALIDATOR_INFO_KEY = new PublicKey(
   'Va1idator1nfo111111111111111111111111111111',
@@ -83,8 +84,10 @@ export class ValidatorInfo {
 
     const configKeys: Array<ConfigKey> = [];
     for (let i = 0; i < 2; i++) {
-      const publicKey = new PublicKey(byteArray.splice(0, PUBLIC_KEY_LENGTH));
-      const isSigner = byteArray.splice(0, 1)[0] === 1;
+      const publicKey = new PublicKey(
+        guardedSplice(byteArray, 0, PUBLIC_KEY_LENGTH),
+      );
+      const isSigner = guardedShift(byteArray) === 1;
       configKeys.push({publicKey, isSigner});
     }
 

packages/library-legacy/test/guarded-array-utils.test.ts

@@ -0,0 +1,52 @@
+import {expect} from 'chai';
+import {spy} from 'sinon';
+
+import {guardedShift, guardedSplice} from '../src/utils/guarded-array-utils';
+
+describe('guardedShift', () => {
+  it('delegates to Array#shift', () => {
+    const arr = [1, 2, 3];
+    const shiftSpy = spy(arr, 'shift');
+    const result = guardedShift(arr);
+    expect(shiftSpy).is.calledWithExactly();
+    expect(result).to.eq(shiftSpy.returnValues[0]);
+  });
+  it('throws when the array is zero-length', () => {
+    const arr: number[] = [];
+    expect(() => guardedShift(arr)).to.throw();
+  });
+});
+
+describe('guardedSplice', () => {
+  it('delegates to Array#splice', () => {
+    const arr = [1, 2, 3];
+    const spliceSpy = spy(arr, 'splice');
+    const result = guardedSplice(
+      arr,
+      /* start */ 0,
+      /* deleteCount */ 3,
+      /* ...items */
+      100,
+      101,
+      102,
+    );
+    expect(spliceSpy).is.calledWithExactly(0, 3, 100, 101, 102);
+    expect(result).to.eq(spliceSpy.returnValues[0]);
+  });
+  it('allows zero-length splices', () => {
+    const arr: number[] = [1, 2, 3];
+    expect(guardedSplice(arr, 0, 0)).to.be.an.empty('array');
+  });
+  it('allows zero-length splices via the `deleteCount` argument being the explicit value `undefined`', () => {
+    const arr: number[] = [1, 2, 3];
+    expect(guardedSplice(arr, 0, undefined)).to.be.an.empty('array');
+  });
+  it('throws when the `start` would take you past the end of the array', () => {
+    const arr: number[] = [1, 2, 3];
+    expect(() => guardedSplice(arr, 3)).to.throw();
+  });
+  it('throws when the `deleteCount` and `start` would take you past the end of the array', () => {
+    const arr: number[] = [1, 2, 3];
+    expect(() => guardedSplice(arr, 1, 3)).to.throw();
+  });
+});