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datastore: fix out-of-bounds index handling in snapshots BTree #2883

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Merged
merged 2 commits into from
Apr 30, 2025
Merged

datastore: fix out-of-bounds index handling in snapshots BTree #2883

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5dc37dc
datastore: fix out-of-bounds index in snapshots BTree
canepat Apr 30, 2025
2fe4a91
datastore: fix out-of-bounds index in snapshots BTree
canepat Apr 30, 2025
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55 changes: 35 additions & 20 deletions silkworm/db/datastore/snapshots/btree/btree.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -24,23 +24,16 @@ BTree::BTree(

using CompareResult = std::pair<int, BytesOrByteView>;

static CompareResult compare_key(
static std::optional<CompareResult> compare_key(
ByteView key,
BTree::DataIndex key_index,
const BTree::KeyValueIndex& index) {
auto data_key = index.lookup_key(key_index);
ensure(data_key.has_value(), [&] { return "out-of-bounds key=" + to_hex(key) + " data_index=" + std::to_string(key_index); });
if (!data_key) {
return std::nullopt;
}
int cmp = ByteView{*data_key}.compare(key);
return {cmp, std::move(*data_key)};
}

static BTree::KeyValueIndex::LookupResult lookup_key_value(
ByteView key,
BTree::DataIndex key_index,
const BTree::KeyValueIndex& index) {
auto result = index.lookup_key_value(key_index, key);
ensure(result.has_value(), [&] { return "out-of-bounds key=" + to_hex(key) + " data_index=" + std::to_string(key_index); });
return std::move(*result);
return CompareResult{cmp, std::move(*data_key)};
}

BTree::SeekResult BTree::seek(ByteView seek_key, const KeyValueIndex& index) {
Expand All @@ -55,8 +48,12 @@ BTree::SeekResult BTree::seek(ByteView seek_key, const KeyValueIndex& index) {
auto [_, left_index, right_index] = binary_search_in_cache(seek_key); // left_index == right_index when key is found
uint64_t median = 0;
while (left_index < right_index) {
if (right_index - left_index <= kDefaultBtreeStartSkip) { // found small range, faster to scan now
const auto [cmp, key] = compare_key(seek_key, left_index, index);
if (right_index - left_index <= kDefaultBtreeStartSkip) { // found a small range, faster to scan now
const auto cmp_result = compare_key(seek_key, left_index, index);
if (!cmp_result) {
return {/*found=*/false, {}, {}, 0};
}
const auto [cmp, key] = *cmp_result;
if (cmp == 0) {
right_index = left_index;
break;
Expand All @@ -71,7 +68,11 @@ BTree::SeekResult BTree::seek(ByteView seek_key, const KeyValueIndex& index) {
break;
}
median = (left_index + right_index) >> 1;
const auto [cmp, key] = compare_key(seek_key, median, index);
const auto cmp_result = compare_key(seek_key, median, index);
if (!cmp_result) {
return {/*found=*/false, {}, {}, 0};
}
const auto [cmp, key] = *cmp_result;
if (cmp == 0) {
left_index = right_index = median;
break;
Expand Down Expand Up @@ -107,7 +108,7 @@ std::optional<BytesOrByteView> BTree::get(ByteView key, const KeyValueIndex& ind
}
auto [_, left_index, right_index] = binary_search_in_cache(key); // left_index == right_index when key is found
while (left_index < right_index) {
if (right_index - left_index <= kDefaultBtreeStartSkip) { // found small range, faster to scan now
if (right_index - left_index <= kDefaultBtreeStartSkip) { // found a small range, faster to scan now
auto value = index.advance_key_value(left_index, key, right_index - left_index);
if (!value) {
left_index = right_index;
Expand All @@ -116,7 +117,11 @@ std::optional<BytesOrByteView> BTree::get(ByteView key, const KeyValueIndex& ind
return value;
}
const uint64_t median = (left_index + right_index) >> 1;
auto [cmp, optional_v] = lookup_key_value(key, median, index);
const auto lookup_result = index.lookup_key_value(median, key);
if (!lookup_result) {
return std::nullopt;
}
const auto [cmp, optional_v] = *lookup_result;
if (cmp == 0) {
SILKWORM_ASSERT(optional_v);
return optional_v;
Expand All @@ -127,7 +132,11 @@ std::optional<BytesOrByteView> BTree::get(ByteView key, const KeyValueIndex& ind
left_index = median + 1;
}
}
auto [cmp, optional_v] = lookup_key_value(key, left_index, index);
const auto lookup_result = index.lookup_key_value(left_index, key);
if (!lookup_result) {
return std::nullopt;
}
const auto [cmp, optional_v] = *lookup_result;
if (cmp != 0) {
return std::nullopt;
}
Expand Down Expand Up @@ -157,7 +166,9 @@ void BTree::warmup(const KeyValueIndex& index) {
const size_t step = num_nodes_ < fanout_ ? 1 : fanout_; // cache all keys if less than M
for (size_t i{step}; i < num_nodes_; i += step) {
const size_t data_index = i - 1;
auto [_, key] = compare_key({}, data_index, index);
auto cmp_result = compare_key({}, data_index, index);
if (!cmp_result) continue;
auto [_, key] = *cmp_result;
cache_.emplace_back(Node{data_index, Bytes{key}});
cached_bytes += sizeof(Node) + ByteView{key}.size();
}
Expand Down Expand Up @@ -185,7 +196,11 @@ BTree::Nodes BTree::decode_nodes(std::span<uint8_t> encoded_nodes) {

void BTree::check_against_data_keys(const KeyValueIndex& index) {
for (const auto& node : cache_) {
const auto [cmp, key] = compare_key(node.key, node.key_index, index);
const auto cmp_result = compare_key(node.key, node.key_index, index);
ensure(cmp_result.has_value(), [&] {
return "out-of-bounds key=" + to_hex(node.key) + " data_index=" + std::to_string(node.key_index);
});
const auto [cmp, key] = *cmp_result;
ensure(cmp == 0, [&]() {
return "key mismatch node.key=" + to_hex(node.key) +
" key=" + to_hex(key) +
Expand Down
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