fix: Prevent invalid gas limit (#5093)

## Explanation

Add hex validation to the `gas` and `gasLimit` properties on `txParams`.

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## References

Fixes: MetaMask/MetaMask-planning#3826

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## Changelog

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### `@metamask/transaction-controller`

- **ADDED**: Hex validation for `gas` and `gasLimit`

## Checklist

- [x] I've updated the test suite for new or updated code as appropriate
- [ ] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [ ] I've highlighted breaking changes using the "BREAKING" category
above as appropriate
- [ ] I've prepared draft pull requests for clients and consumer
packages to resolve any breaking changes

packages/transaction-controller/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Validate `gas` and `gasLimit` are hexadecimal strings ([#5093](https://github.com/MetaMask/core/pull/5093))
+
 ### Changed
 
 - Bump `@metamask/base-controller` from `^7.0.0` to `^7.1.0` ([#5079](https://github.com/MetaMask/core/pull/5079))

packages/transaction-controller/src/utils/validation.test.ts

@@ -1,6 +1,7 @@
 import { rpcErrors } from '@metamask/rpc-errors';
 
 import { TransactionEnvelopeType } from '../types';
+import type { TransactionParams } from '../types';
 import { validateTxParams } from './validation';
 
 describe('validation', () => {
@@ -362,6 +363,60 @@ describe('validation', () => {
           } as any),
         ).not.toThrow();
       });
+
+      it('throws if gasLimit is defined but not a valid hexadecimal', () => {
+        expect(() =>
+          validateTxParams({
+            from: '0x1678a085c290ebd122dc42cba69373b5953b831d',
+            to: '0xfbb5595c18ca76bab52d66188e4ca50c7d95f77a',
+            maxFeePerGas: '0x01',
+            gasLimit: 'zzzzz',
+            // TODO: Replace `any` with type
+            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+          } as any),
+        ).toThrow(
+          rpcErrors.invalidParams(
+            'Invalid transaction params: gasLimit is not a valid hexadecimal. got: (zzzzz)',
+          ),
+        );
+        expect(() =>
+          validateTxParams({
+            from: '0x1678a085c290ebd122dc42cba69373b5953b831d',
+            to: '0xfbb5595c18ca76bab52d66188e4ca50c7d95f77a',
+            maxFeePerGas: '0x01',
+            gasLimit: '0x0',
+            // TODO: Replace `any` with type
+            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+          } as any),
+        ).not.toThrow();
+      });
+
+      it('throws if gas is defined but not a valid hexadecimal', () => {
+        expect(() =>
+          validateTxParams({
+            from: '0x1678a085c290ebd122dc42cba69373b5953b831d',
+            to: '0xfbb5595c18ca76bab52d66188e4ca50c7d95f77a',
+            maxFeePerGas: '0x01',
+            gas: 'zzzzz',
+            // TODO: Replace `any` with type
+            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+          } as unknown as TransactionParams),
+        ).toThrow(
+          rpcErrors.invalidParams(
+            'Invalid transaction params: gas is not a valid hexadecimal. got: (zzzzz)',
+          ),
+        );
+        expect(() =>
+          validateTxParams({
+            from: '0x1678a085c290ebd122dc42cba69373b5953b831d',
+            to: '0xfbb5595c18ca76bab52d66188e4ca50c7d95f77a',
+            maxFeePerGas: '0x01',
+            gas: '0x0',
+            // TODO: Replace `any` with type
+            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+          } as unknown as TransactionParams),
+        ).not.toThrow();
+      });
     });
   });
 });

packages/transaction-controller/src/utils/validation.ts

@@ -7,7 +7,12 @@ import { isStrictHexString } from '@metamask/utils';
 import { TransactionEnvelopeType, type TransactionParams } from '../types';
 import { isEIP1559Transaction } from './utils';
 
-type GasFieldsToValidate = 'gasPrice' | 'maxFeePerGas' | 'maxPriorityFeePerGas';
+type GasFieldsToValidate =
+  | 'gasPrice'
+  | 'maxFeePerGas'
+  | 'maxPriorityFeePerGas'
+  | 'gas'
+  | 'gasLimit';
 
 /**
  * Validates whether a transaction initiated by a specific 'from' address is permitted by the origin.
@@ -281,6 +286,14 @@ function validateGasFeeParams(txParams: TransactionParams) {
     );
     ensureFieldIsValidHex(txParams, 'maxPriorityFeePerGas');
   }
+
+  if (txParams.gasLimit) {
+    ensureFieldIsValidHex(txParams, 'gasLimit');
+  }
+
+  if (txParams.gas) {
+    ensureFieldIsValidHex(txParams, 'gas');
+  }
 }
 
 /**