From f69be6fadcf21cf9011dcdce2ded475f2aabbcff Mon Sep 17 00:00:00 2001
From: Say Cheong <greymistcube@gmail.com>
Date: Mon, 4 Dec 2023 19:09:07 +0900
Subject: [PATCH] Do not allow negative gas price or negative gas limit

---
 Lib9c.Policy/Policy/BlockPolicySource.cs | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/Lib9c.Policy/Policy/BlockPolicySource.cs b/Lib9c.Policy/Policy/BlockPolicySource.cs
index 28df6ce2ec..634274d7bf 100644
--- a/Lib9c.Policy/Policy/BlockPolicySource.cs
+++ b/Lib9c.Policy/Policy/BlockPolicySource.cs
@@ -229,12 +229,21 @@ internal static TxPolicyViolationException ValidateNextBlockTxRaw(
                             return null;
                     }
                 }
-                if (transaction.MaxGasPrice is null || transaction.GasLimit is null)
+
+                if (!(transaction.MaxGasPrice is { } gasPrice && transaction.GasLimit is { } gasLimit))
+                {
+                    return new TxPolicyViolationException(
+                        "Transaction has no gas price or limit.",
+                        transaction.Id);
+                }
+
+                if (gasPrice.Sign < 0 || gasLimit < 0)
                 {
-                    return new
-                        TxPolicyViolationException("Transaction has no gas price or limit.",
+                    return new TxPolicyViolationException(
+                        "Transaction has negative gas price or limit.",
                         transaction.Id);
                 }
+
                 if (transaction.MaxGasPrice * transaction.GasLimit > blockChain.GetBalance(transaction.Signer, Currencies.Mead))
                 {
                     return new TxPolicyViolationException(