From 0617d6e02efa045e3ecd34cdef2fc470213510e1 Mon Sep 17 00:00:00 2001
From: Ed Hennis <ed@ripple.com>
Date: Fri, 18 Nov 2022 18:04:39 -0500
Subject: [PATCH] Don't try to read SLE with key 0 from the ledger:

* May resolve #4341
---
 src/ripple/app/tx/impl/NFTokenAcceptOffer.cpp |  3 +++
 src/test/app/NFToken_test.cpp                 | 12 ++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/src/ripple/app/tx/impl/NFTokenAcceptOffer.cpp b/src/ripple/app/tx/impl/NFTokenAcceptOffer.cpp
index fb5f51c7251..07fe9957a76 100644
--- a/src/ripple/app/tx/impl/NFTokenAcceptOffer.cpp
+++ b/src/ripple/app/tx/impl/NFTokenAcceptOffer.cpp
@@ -67,6 +67,9 @@ NFTokenAcceptOffer::preclaim(PreclaimContext const& ctx)
         -> std::pair<std::shared_ptr<const SLE>, TER> {
         if (id)
         {
+            if (id->isZero())
+                return {nullptr, tecOBJECT_NOT_FOUND};
+
             auto offerSLE = ctx.view.read(keylet::nftoffer(*id));
 
             if (!offerSLE)
diff --git a/src/test/app/NFToken_test.cpp b/src/test/app/NFToken_test.cpp
index ac86bf74988..2fb27f8a352 100644
--- a/src/test/app/NFToken_test.cpp
+++ b/src/test/app/NFToken_test.cpp
@@ -1130,6 +1130,12 @@ class NFToken_test : public beast::unit_test::suite
         //----------------------------------------------------------------------
         // preclaim
 
+        // The buy offer must be non-zero.
+        env(token::acceptBuyOffer(buyer, beast::zero),
+            ter(tecOBJECT_NOT_FOUND));
+        env.close();
+        BEAST_EXPECT(ownerCount(env, buyer) == 0);
+
         // The buy offer must be present in the ledger.
         uint256 const missingOfferIndex = keylet::nftoffer(alice, 1).key;
         env(token::acceptBuyOffer(buyer, missingOfferIndex),
@@ -1142,6 +1148,12 @@ class NFToken_test : public beast::unit_test::suite
         env.close();
         BEAST_EXPECT(ownerCount(env, buyer) == 0);
 
+        // The sell offer must be non-zero.
+        env(token::acceptSellOffer(buyer, beast::zero),
+            ter(tecOBJECT_NOT_FOUND));
+        env.close();
+        BEAST_EXPECT(ownerCount(env, buyer) == 0);
+
         // The sell offer must be present in the ledger.
         env(token::acceptSellOffer(buyer, missingOfferIndex),
             ter(tecOBJECT_NOT_FOUND));