Validate code_size during deserialization to prevent oversized allocations#5151
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Validate code_size during deserialization to prevent oversized allocations#5151scsiguy wants to merge 2 commits into
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…lization (facebookresearch#5147) Summary: Index2Layer deserialization reads its sub-quantizer via read_index() which allocates a new Index on the heap, but never sets q1.own_fields = true. Since Level1Quantizer::own_fields defaults to false, the deserialized Index2Layer does not own its quantizer and never frees it — leaking the allocation both on the normal path (when the Index2Layer is eventually destroyed) and on the error path (when a subsequent deserialization step throws and the partially-constructed Index2Layer is cleaned up). Every other index type in read_index_up that reads a sub-index via read_index sets own_fields = true afterwards (IndexIVF, IndexPreTransform, IndexIDMap, IndexRefine, IndexHNSW, IndexNSG, IndexNNDescent, etc.). Index2Layer was the only one missing it. Reviewed By: mnorris11 Differential Revision: D102357926
…tions Summary: Several index types read code_size directly from the serialized stream independently of the quantizer parameters that determine its correct value. When the stored code_size is corrupt but ntotal is 0, the existing consistency check (codes.size() == ntotal * code_size) passes trivially. A subsequent search then allocates (code_size * sizeof(float)) bytes in GenericFlatCodesDistanceComputer, which can trigger an OOM exception. Two layers of protection: 1. Cross-validate the deserialized code_size against the quantizer-derived value for all index types that read code_size from the stream: IndexResidualQuantizer, IndexLocalSearchQuantizer, IndexProductResidualQuantizer, IndexProductLocalSearchQuantizer, IndexIVFAdditiveQuantizer, IndexIVFScalarQuantizer, IndexLSH, and Index2Layer. The quantizer code_size is computed from validated parameters via set_derived_values() and is always authoritative. 2. For IndexLattice, where code_size is derived from constructor parameters (scale_nbit, lattice_nbit, nsq) rather than read from the stream, validate that code_size does not exceed the uncompressed vector size (d * sizeof(float)). IndexLattice is a lossy compressor, so its code_size must always be smaller than the uncompressed representation. A corrupt scale_nbit can overflow the total_nbit computation, producing a code_size that wraps to a huge value; this bound catches that before any allocation is attempted. Reviewed By: mnorris11 Differential Revision: D102360605
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@scsiguy has exported this pull request. If you are a Meta employee, you can view the originating Diff in D102360605. |
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This pull request has been merged in 6c70444. |
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Summary:
Several index types read code_size directly from the serialized stream independently of the quantizer parameters that determine its correct value. When the stored code_size is corrupt but ntotal is 0, the existing consistency check (codes.size() == ntotal * code_size) passes trivially. A subsequent search then allocates (code_size * sizeof(float)) bytes in GenericFlatCodesDistanceComputer, which can trigger an OOM exception.
Two layers of protection:
Cross-validate the deserialized code_size against the quantizer-derived value for all index types that read code_size from the stream: IndexResidualQuantizer, IndexLocalSearchQuantizer, IndexProductResidualQuantizer, IndexProductLocalSearchQuantizer, IndexIVFAdditiveQuantizer, IndexIVFScalarQuantizer, IndexLSH, and Index2Layer. The quantizer code_size is computed from validated parameters via set_derived_values() and is always authoritative.
For IndexLattice, where code_size is derived from constructor parameters (scale_nbit, lattice_nbit, nsq) rather than read from the stream, validate that code_size does not exceed the uncompressed vector size (d * sizeof(float)). IndexLattice is a lossy compressor, so its code_size must always be smaller than the uncompressed representation. A corrupt scale_nbit can overflow the total_nbit computation, producing a code_size that wraps to a huge value; this bound catches that before any allocation is attempted.
Reviewed By: mnorris11
Differential Revision: D102360605