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[6.1.6] Add TDS token data length bounds checks (#4340) - #4359
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Re-implementation of b6c0569 for the release/6.1 branch layout. Adds bounds checks to TDS token parsing to prevent unbounded memory allocation from a malicious server spoofing length fields: - ENV_PROMOTETRANSACTION: reject > 64 KB - FeatureExtAck data: reject > 1 MB - SessionState total + per-state: reject > 1 MB - FedAuthInfo: reject > 1 MB - ReturnValue: reject > int.MaxValue (was silent truncation) - TryReadSqlDateTime: reject > 10 bytes (max DateTimeOffset wire size) - SQLVECTOR/binary: reject > MAXSIZE Also adds bounds check in SqlInternalConnectionTds session recovery parsing to prevent buffer overread from spoofed state lengths. New constants: TdsEnums.MaxTokenDataLength (1 MB), MaxPromoteTransactionLength (64 KB), MaxDateTimeLength (10). New tests: FeatureExtAckBoundsTests (2 tests), TdsTokenBoundsTests (12 tests) using simulated TDS server.
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Pull request overview
This PR hardens TDS token parsing in Microsoft.Data.SqlClient by adding upper-bound validation to length fields read from the wire, preventing unbounded allocations (and related OOB risks) when connected to a malicious or corrupted server.
Changes:
- Added maximum length constants (1 MB token payload cap, 64 KB promote-transaction cap, 10-byte datetime cap) and enforced them during token parsing.
- Converted several debug-only assertions into runtime validation that throws
SQL.ParsingErrorLength(ParsingErrorState.CorruptedTdsStream, ...). - Added simulated-server infrastructure and new unit tests covering the new bounds checks.
Reviewed changes
Copilot reviewed 10 out of 10 changed files in this pull request and generated 6 comments.
Show a summary per file
| File | Description |
|---|---|
| src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsEnums.cs | Introduces new max-length constants used by the parser. |
| src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SqlUtil.cs | Adds ParsingErrorLength overload for uint lengths. |
| src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParser.cs | Adds bounds checks to multiple token parsing paths (netcore). |
| src/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/TdsParser.cs | Adds bounds checks to multiple token parsing paths (netfx). |
| src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlInternalConnectionTds.cs | Validates SRECOVERY inner-state lengths before copying state buffers (netcore). |
| src/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/SqlInternalConnectionTds.cs | Validates SRECOVERY inner-state lengths before copying state buffers (netfx). |
| src/Microsoft.Data.SqlClient/tests/tools/TDS/TDS.Servers/GenericTdsServer.cs | Adds a hook to mutate SQL batch responses for simulated server tests. |
| src/Microsoft.Data.SqlClient/tests/UnitTests/SimulatedServerTests/Fixtures/TdsServerFixture.cs | New fixture to manage per-test TDS server lifecycle. |
| src/Microsoft.Data.SqlClient/tests/UnitTests/SimulatedServerTests/FeatureExtAckBoundsTests.cs | New tests for FeatureExtAck payload length bounds. |
| src/Microsoft.Data.SqlClient/tests/UnitTests/SimulatedServerTests/TdsTokenBoundsTests.cs | New comprehensive tests for bounds checks across multiple token types. |
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Description
Re-implementation of #4340 (
b6c05695a) for therelease/6.1branch layout.Adds bounds checks to TDS token parsing to prevent unbounded memory allocation from a malicious server spoofing length fields.
Bounds checks added
ENV_PROMOTETRANSACTIONTryProcessFeatureExtAckdata lengthTryProcessSessionStatetotal lengthTryProcessSessionStateper-state lengthTryProcessFedAuthInfotoken lengthTryProcessReturnValuevalue lengthTryReadSqlDateTimelengthSQLVECTOR/binary readSqlInternalConnectionTdssession recoveryNew constants
TdsEnums.MaxTokenDataLength= 1 MBTdsEnums.MaxPromoteTransactionLength= 64 KBTdsEnums.MaxDateTimeLength= 10New tests (14 total)
FeatureExtAckBoundsTests(2 tests) — oversized feature ext ack dataTdsTokenBoundsTests(12 tests) — all other bounds checks via simulated TDS serverTest infrastructure additions
GenericTdsServer.OnSQLBatchCompleteddelegate hookTdsServerFixturexunit fixture classFiles changed
src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsEnums.cssrc/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/SqlUtil.cssrc/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParser.cssrc/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/TdsParser.cssrc/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlInternalConnectionTds.cssrc/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/SqlInternalConnectionTds.cssrc/Microsoft.Data.SqlClient/tests/tools/TDS/TDS.Servers/GenericTdsServer.cstests/UnitTests/SimulatedServerTests/Fixtures/TdsServerFixture.cstests/UnitTests/SimulatedServerTests/FeatureExtAckBoundsTests.cstests/UnitTests/SimulatedServerTests/TdsTokenBoundsTests.csVerification
Fixes #4340