From c7890b7d2ba359ca4dec193e8a1cd11fb0237819 Mon Sep 17 00:00:00 2001
From: Konstantin Akimov <knstqq@gmail.com>
Date: Tue, 29 Jul 2025 21:03:21 +0700
Subject: [PATCH 1/2] fix: avoid possible nullptr for unknown hash of qc after
 LookupBlockIndex

---
 src/llmq/blockprocessor.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/llmq/blockprocessor.cpp b/src/llmq/blockprocessor.cpp
index 17c7d562c7d99..d8a8d74c1184c 100644
--- a/src/llmq/blockprocessor.cpp
+++ b/src/llmq/blockprocessor.cpp
@@ -219,6 +219,11 @@ bool CQuorumBlockProcessor::ProcessBlock(const CBlock& block, gsl::not_null<cons
         for (const auto& [_, qc] : qcs) {
             if (qc.IsNull()) continue;
             const auto* pQuorumBaseBlockIndex = m_chainstate.m_blockman.LookupBlockIndex(qc.quorumHash);
+            if (pQuorumBaseBlockIndex == nullptr) {
+                LogPrint(BCLog::LLMQ, "[ProcessBlock] h[%d] unexpectedly failed due to no known pindex for hash[%s]\n",
+                         pindex->nHeight, qc.quorumHash.ToString());
+                return false;
+            }
             qc.VerifySignatureAsync(m_dmnman, m_qsnapman, pQuorumBaseBlockIndex, &queue_control);
         }
 
@@ -334,6 +339,11 @@ bool CQuorumBlockProcessor::ProcessCommitment(int nHeight, const uint256& blockH
     }
 
     const auto* pQuorumBaseBlockIndex = m_chainstate.m_blockman.LookupBlockIndex(qc.quorumHash);
+    if (pQuorumBaseBlockIndex == nullptr) {
+        LogPrint(BCLog::LLMQ, "%s -- unexpectedly failed due to no known pindex for hash[%s]\n", __func__,
+                 qc.quorumHash.ToString());
+        return false;
+    }
 
     // we don't validate signatures here; they already validated on previous step
     if (!qc.Verify(m_dmnman, m_qsnapman, pQuorumBaseBlockIndex, /*checksigs=*/false)) {

From 3b9e061b02b8e33741268604f4513dde9532b5dd Mon Sep 17 00:00:00 2001
From: Konstantin Akimov <knstqq@gmail.com>
Date: Thu, 21 Aug 2025 14:55:48 +0700
Subject: [PATCH 2/2] fix: handle possible nullptr in InitNewQuorum

---
 src/llmq/dkgsessionhandler.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/llmq/dkgsessionhandler.cpp b/src/llmq/dkgsessionhandler.cpp
index 306b74b91b079..c5dfcce1acfd2 100644
--- a/src/llmq/dkgsessionhandler.cpp
+++ b/src/llmq/dkgsessionhandler.cpp
@@ -539,7 +539,7 @@ void CDKGSessionHandler::HandleDKGRound(CConnman& connman, PeerManager& peerman)
 
     const CBlockIndex* pQuorumBaseBlockIndex = WITH_LOCK(::cs_main, return m_chainstate.m_blockman.LookupBlockIndex(curQuorumHash));
 
-    if (!InitNewQuorum(pQuorumBaseBlockIndex)) {
+    if (!pQuorumBaseBlockIndex || !InitNewQuorum(pQuorumBaseBlockIndex)) {
         // should actually never happen
         WaitForNewQuorum(curQuorumHash);
         throw AbortPhaseException();