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https://github.com/facebookresearch/faiss.git
synced 2026-10-11 22:50:00 +00:00
Justin Gibbs
66853ee41d
Summary: Pull Request resolved: https://github.com/facebookresearch/faiss/pull/4804 Valid neighbor indexes are in the range of [0, ntotal). Fix range check in NSG::search_on_graph() that accepted an index value of ntotal. NOTE: This data structure uses -1 as a termninal sentinal. The call to nsg::Graph::get_neighgbors() above the for loop that includes the upper bound check stops when encountering a negative index. This means the check for negative values has already occurred and does not need to be repeated inside the loop. Reviewed By: junjieqi, sh00s Differential Revision: D93040548 fbshipit-source-id: e1bde990a459c86dfaebdd2f780375b7922fc5f5
65 lines
1.8 KiB
C++
65 lines
1.8 KiB
C++
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include <gtest/gtest.h>
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#include <cstring>
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#include <memory>
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#include <vector>
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#include <faiss/Index.h>
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#include <faiss/IndexFlat.h>
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#include <faiss/IndexNSG.h>
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#include <faiss/utils/random.h>
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using namespace faiss;
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TEST(IoCorrupted, NSGNeighborIdEqualsNtotal) {
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// Build an NSG index
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int d = 8, nb = 500;
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std::vector<float> xb(nb * d);
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faiss::rand_smooth_vectors(nb, d, xb.data(), 1234);
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IndexNSGFlat index(d, 16);
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index.add(nb, xb.data());
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// Verify that NSG::search_on_graph() skips corrupt neighbor entries
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// that would trigger access outside/above the bounds of the index by
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// setting the LAST valid neighbor of every node to ntotal.
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// get_neighbors returns neighbors until it hits a -1 sentinel,
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// so setting the last non-sentinel entry preserves graph connectivity
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// while ensuring the inner search loop encounters id == ntotal.
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auto* graph = index.nsg.final_graph.get();
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for (int i = 0; i < nb; i++) {
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// Find the last valid (non-sentinel) neighbor slot
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int last = -1;
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for (int j = 0; j < graph->K; j++) {
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if (graph->at(i, j) >= 0) {
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last = j;
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} else {
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break;
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}
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}
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if (last >= 0) {
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graph->at(i, last) = nb; // inject ntotal
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}
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}
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std::vector<float> xq(d);
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faiss::rand_smooth_vectors(1, d, xq.data(), 5678);
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std::vector<idx_t> I(1);
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std::vector<float> D(1);
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// Safely skipped without an exception or ASAN failure.
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EXPECT_NO_THROW(index.search(1, xq.data(), 1, D.data(), I.data()));
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// Result must be a valid node ID
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EXPECT_GE(I[0], 0);
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EXPECT_LT(I[0], nb);
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}
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