fix: add check in batch_score function to prevent query node seg fault (#46025)

previously we saw that when doing reranker with phrase matching, the
query node throws a segmentation fault error.

github issue link: https://github.com/milvus-io/milvus/issues/45990

---------

Signed-off-by: Xinyi Jiang <xinyi.jiang@reddit.com>
Co-authored-by: Xinyi Jiang <xinyi.jiang@reddit.com>

internal/core/src/rescores/Scorer.cpp

@@ -48,10 +48,18 @@ WeightScorer::batch_score(milvus::OpContext* op_ctx,
                           const FixedVector<int32_t>& offsets,
                           const TargetBitmap& bitmap,
                           std::vector<std::optional<float>>& boost_scores) {
+    auto bitmap_size = bitmap.size();
     for (auto i = 0; i < offsets.size(); i++) {
-        if (bitmap[offsets[i]] > 0) {
-            set_score(boost_scores[i], mode);
+        auto offset = offsets[i];
+        // Bounds check: offset must be within bitmap size.
+        // Race condition: text index may lag behind vector index,
+        // causing offsets to reference rows not yet in text index.
+        if (offset >= 0 && static_cast<size_t>(offset) < bitmap_size) {
+            if (bitmap[offset] > 0) {
+                set_score(boost_scores[i], mode);
+            }
         }
+        // If offset is out of bounds, treat as "no match" (don't apply boost)
     }
 };
 
@@ -163,9 +171,9 @@ RandomScorer::random_score(milvus::OpContext* op_ctx,
                    "now only support int64 field as seed");
         // TODO: Support varchar and int32 field as random field.
 
-        auto datas = array->scalars().long_data();
-        for (int i = 0; i < datas.data_size(); i++) {
-            auto a = datas.data()[i];
+        auto data = array->scalars().long_data();
+        for (int i = 0; i < data.data_size(); i++) {
+            auto a = data.data()[i];
             auto random_score =
                 hash_to_double(MurmurHash3_x64_64_Special(a, seed_));
             if (idx == nullptr) {

internal/core/unittest/CMakeLists.txt

@@ -43,6 +43,7 @@ set(MILVUS_TEST_FILES
         test_index_wrapper.cpp
         test_integer_overflow.cpp
         test_query.cpp
+        test_scorer.cpp
         test_sealed.cpp
         test_storage.cpp
         test_string_expr.cpp

internal/core/unittest/test_scorer.cpp

@@ -0,0 +1,84 @@
+// Copyright (C) 2019-2020 Zilliz. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software distributed under the License
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+// or implied. See the License for the specific language governing permissions and limitations under the License
+
+#include <gtest/gtest.h>
+#include <optional>
+#include <vector>
+
+#include "common/Types.h"
+#include "rescores/Scorer.h"
+#include "pb/plan.pb.h"
+
+using namespace milvus;
+using namespace milvus::rescores;
+
+class WeightScorerTest : public ::testing::Test {
+ protected:
+    void
+    SetUp() override {
+        // Create a WeightScorer with no filter and weight of 2.0
+        scorer_ = std::make_unique<WeightScorer>(nullptr, 2.0f);
+    }
+
+    std::unique_ptr<WeightScorer> scorer_;
+};
+
+// Test: TargetBitmap batch_score with valid offsets (all within bitmap bounds)
+TEST_F(WeightScorerTest, BatchScoreTargetBitmapValidOffsets) {
+    TargetBitmap bitmap(100);
+    bitmap.set(10);
+    bitmap.set(50);
+    bitmap.set(90);
+
+    // Offsets that are all within bitmap bounds
+    FixedVector<int32_t> offsets = {10, 20, 50, 90};
+    std::vector<std::optional<float>> boost_scores(offsets.size(),
+                                                   std::nullopt);
+
+    proto::plan::FunctionMode mode = proto::plan::FunctionMode::FunctionModeSum;
+
+    scorer_->batch_score(nullptr, nullptr, mode, offsets, bitmap, boost_scores);
+
+    // Positions 10, 50, 90 should have scores (they are set in bitmap)
+    EXPECT_TRUE(boost_scores[0].has_value());
+    EXPECT_FALSE(boost_scores[1].has_value());
+    EXPECT_TRUE(boost_scores[2].has_value());
+    EXPECT_TRUE(boost_scores[3].has_value());
+}
+
+// Test: TargetBitmap batch_score with out-of-bounds offsets (should NOT crash)
+TEST_F(WeightScorerTest, BatchScoreTargetBitmapOutOfBoundsOffsets) {
+    // Create a small bitmap of size 50
+    TargetBitmap bitmap(50);
+    bitmap.set(10);  // Set bit at position 10
+    bitmap.set(40);  // Set bit at position 40
+
+    // Offsets where some are OUT OF BOUNDS (>= 50)
+    // This simulates the race condition where text index lags behind vector index
+    FixedVector<int32_t> offsets = {10, 40, 60, 100, 200};
+    std::vector<std::optional<float>> boost_scores(offsets.size(),
+                                                   std::nullopt);
+
+    proto::plan::FunctionMode mode = proto::plan::FunctionMode::FunctionModeSum;
+
+    // Should NOT crash! Out-of-bounds offsets should be safely skipped
+    ASSERT_NO_THROW(scorer_->batch_score(
+        nullptr, nullptr, mode, offsets, bitmap, boost_scores));
+
+    // In-bounds offsets should be scored correctly
+    EXPECT_TRUE(boost_scores[0].has_value());
+    EXPECT_TRUE(boost_scores[1].has_value());
+
+    // Out-of-bounds offsets should NOT have scores (safely skipped)
+    EXPECT_FALSE(boost_scores[2].has_value());
+    EXPECT_FALSE(boost_scores[3].has_value());
+    EXPECT_FALSE(boost_scores[4].has_value());
+}