From 0e10937184438f8d81940336b183267e59f959b7 Mon Sep 17 00:00:00 2001
From: Andrew Toth <andrewstoth@gmail.com>
Date: Fri, 13 Mar 2026 13:32:12 -0400
Subject: [PATCH] fuzz: add coins_view_stacked fuzz harness to test concurrent
 leveldb reads

---
 src/test/fuzz/coins_view.cpp | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/test/fuzz/coins_view.cpp b/src/test/fuzz/coins_view.cpp
index 62f7461442d..52c7f031dc7 100644
--- a/src/test/fuzz/coins_view.cpp
+++ b/src/test/fuzz/coins_view.cpp
@@ -449,3 +449,25 @@ FUZZ_TARGET(coins_view_overlay, .init = initialize_coins_view) EXCLUSIVE_LOCKS_R
     const auto reset_guard{coins_view_cache.StartFetching(block)};
     TestCoinsView(fuzzed_data_provider, coins_view_cache, &backend_cache);
 }
+
+FUZZ_TARGET(coins_view_stacked, .init = initialize_coins_view) EXCLUSIVE_LOCKS_REQUIRED(!g_thread_pool_mutex)
+{
+    SeedRandomStateForTest(SeedRand::ZEROS); // for SaltedTxidHasher
+    StartPoolIfNeeded();
+    FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
+    auto db_params = DBParams{
+        .path = "",
+        .cache_bytes = 1_MiB,
+        .memory_only = true,
+    };
+    CCoinsViewDB backend_base_coins_view{std::move(db_params), CoinsViewOptions{}};
+    CCoinsViewCache backend_cache{&backend_base_coins_view, /*deterministic=*/true};
+    TestCoinsView(fuzzed_data_provider, backend_cache, &backend_base_coins_view);
+    CoinsViewOverlay coins_view_cache{&backend_cache, g_thread_pool, /*deterministic=*/true};
+    CBlock block{BuildRandomBlock(fuzzed_data_provider, backend_base_coins_view)};
+    {
+        const auto reset_guard{coins_view_cache.StartFetching(block)};
+        TestCoinsView(fuzzed_data_provider, coins_view_cache, &backend_cache);
+    }
+    TestCoinsView(fuzzed_data_provider, backend_cache, &backend_base_coins_view);
+}