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cpp: model Protocol Buffers parse/serialize taint flow #22448

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cpp: model Protocol Buffers parse/serialize taint flow
kumarak Aug 27, 2026
5f0b3df
Update cpp/ql/lib/change-notes/2026-08-27-protobuf-models.md
kumarak Aug 28, 2026
d0b3dd5
fix(cpp): correct protobuf string parse models and expand test coverage
kumarak Aug 28, 2026
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4 changes: 4 additions & 0 deletions cpp/ql/lib/change-notes/2026-08-27-protobuf-models.md
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---
category: minorAnalysis
---
* Added flow summaries for the Protocol Buffers C++ API (`google::protobuf::MessageLite`, covering `Message` and all generated messages).

@jketema jketema Aug 31, 2026

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* Added flow summaries for the Protocol Buffers C++ API (`google::protobuf::MessageLite`, covering `Message` and all generated messages).
* Added flow summaries for the Protocol Buffers `google::protobuf::MessageLite` C++ API.

65 changes: 65 additions & 0 deletions cpp/ql/lib/ext/Protobuf.model.yml
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extensions:
- addsTo:
pack: codeql/cpp-all
extensible: summaryModel
data: # namespace, type, subtypes, name, signature, ext, input, output, kind, provenance
# Flow summaries for the Protocol Buffers C++ API. All of these methods are declared on
# `google::protobuf::MessageLite`; `subtypes` covers `Message` and every generated message.
#
# File-descriptor variants (`{Parse,Serialize}*FromFileDescriptor`) are intentionally omitted:
# the descriptor is an `int`, not a data buffer, so there is no buffer argument to model.
Comment on lines +6 to +10

@jketema jketema Aug 31, 2026

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# Flow summaries for the Protocol Buffers C++ API. All of these methods are declared on
# `google::protobuf::MessageLite`; `subtypes` covers `Message` and every generated message.
#
# File-descriptor variants (`{Parse,Serialize}*FromFileDescriptor`) are intentionally omitted:
# the descriptor is an `int`, not a data buffer, so there is no buffer argument to model.
# File-descriptor variants (`{Parse,Serialize}*FromFileDescriptor`) are intentionally omitted:
# the descriptor is an `int`, not a data buffer, so there is no buffer argument to model.


# Deserialization: the encoded input taints the message (`this`). The `*FromString` methods each
# have a `string_view` overload (the buffer is the by-value argument, so `Argument[0]`) and a
# `const Cord &` overload (the buffer is behind a reference, so `Argument[*0]`). The remaining
# inputs below are pointers or references, so they take `Argument[*0]`.
Comment on lines +12 to +15

@jketema jketema Aug 31, 2026

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# Deserialization: the encoded input taints the message (`this`). The `*FromString` methods each
# have a `string_view` overload (the buffer is the by-value argument, so `Argument[0]`) and a
# `const Cord &` overload (the buffer is behind a reference, so `Argument[*0]`). The remaining
# inputs below are pointers or references, so they take `Argument[*0]`.
# Deserialization

- ["google::protobuf", "MessageLite", True, "ParseFromString", "(string_view)", "", "Argument[0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParseFromString", "(const Cord &)", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParsePartialFromString", "(string_view)", "", "Argument[0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParsePartialFromString", "(const Cord &)", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "MergeFromString", "(string_view)", "", "Argument[0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "MergeFromString", "(const Cord &)", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "MergePartialFromString", "(string_view)", "", "Argument[0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "MergePartialFromString", "(const Cord &)", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParseFromArray", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParsePartialFromArray", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParseFromCord", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParsePartialFromCord", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "MergeFromCord", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "MergePartialFromCord", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParseFromIstream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParsePartialFromIstream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParseFromZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParsePartialFromZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParseFromBoundedZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParsePartialFromBoundedZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "MergeFromBoundedZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
Comment on lines +32 to +36
- ["google::protobuf", "MessageLite", True, "MergePartialFromBoundedZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParseFromCodedStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "ParsePartialFromCodedStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "MergeFromCodedStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "MergePartialFromCodedStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"]

# Serialization into an output buffer/stream: the message (`this`) taints `Argument[*0]`.

@jketema jketema Aug 31, 2026

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# Serialization into an output buffer/stream: the message (`this`) taints `Argument[*0]`.
# Serialization

- ["google::protobuf", "MessageLite", True, "SerializeToString", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializePartialToString", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "AppendToString", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "AppendPartialToString", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializeToArray", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializePartialToArray", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializeToCord", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializePartialToCord", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "AppendToCord", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "AppendPartialToCord", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializeToOstream", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializePartialToOstream", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializeToZeroCopyStream", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializePartialToZeroCopyStream", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializeToCodedStream", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializePartialToCodedStream", "", "", "Argument[-1]", "Argument[*0]", "taint", "manual"]

# Serialization returning the bytes: the message (`this`) taints the (by-value) return value.

@jketema jketema Aug 31, 2026

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# Serialization returning the bytes: the message (`this`) taints the (by-value) return value.
# Serialization returning bytes

- ["google::protobuf", "MessageLite", True, "SerializeAsString", "", "", "Argument[-1]", "ReturnValue", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializePartialAsString", "", "", "Argument[-1]", "ReturnValue", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializeAsCord", "", "", "Argument[-1]", "ReturnValue", "taint", "manual"]
- ["google::protobuf", "MessageLite", True, "SerializePartialAsCord", "", "", "Argument[-1]", "ReturnValue", "taint", "manual"]
35 changes: 35 additions & 0 deletions cpp/ql/test/library-tests/dataflow/external-models/flow.expected
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Expand Up @@ -96,6 +96,9 @@ models
| 95 | Summary: Azure::Core::IO; BodyStream; true; ReadToEnd; ; ; Argument[-1]; ReturnValue.Element; taint; manual |
| 96 | Summary: Azure; Nullable; true; Value; ; ; Argument[-1]; ReturnValue[*]; taint; manual |
| 97 | Summary: boost::asio; ; false; buffer; ; ; Argument[*0]; ReturnValue; taint; manual |
| 98 | Summary: google::protobuf; MessageLite; true; ParseFromArray; ; ; Argument[*0]; Argument[-1]; taint; manual |
| 99 | Summary: google::protobuf; MessageLite; true; SerializeAsString; ; ; Argument[-1]; ReturnValue; taint; manual |
| 100 | Summary: google::protobuf; MessageLite; true; SerializeToArray; ; ; Argument[-1]; Argument[*0]; taint; manual |
edges
| asio_streams.cpp:87:34:87:44 | read_until output argument | asio_streams.cpp:91:7:91:17 | recv_buffer | provenance | Src:MaD:56 |
| asio_streams.cpp:87:34:87:44 | read_until output argument | asio_streams.cpp:93:29:93:39 | recv_buffer | provenance | Src:MaD:56 Sink:MaD:4 |
Expand Down Expand Up @@ -144,6 +147,21 @@ edges
| azure.cpp:294:38:294:53 | call to operator[] | azure.cpp:295:10:295:20 | contentType | provenance | |
| azure.cpp:294:38:294:53 | call to operator[] | azure.cpp:295:10:295:20 | contentType | provenance | |
| azure.cpp:295:10:295:20 | contentType | azure.cpp:295:10:295:20 | contentType | provenance | |
| protobuf.cpp:140:33:140:40 | call to source | protobuf.cpp:141:21:141:31 | *call to data | provenance | TaintFunction |
| protobuf.cpp:141:2:141:4 | ParseFromArray output argument | protobuf.cpp:143:2:143:4 | *msg | provenance | |
| protobuf.cpp:141:21:141:31 | *call to data | protobuf.cpp:141:2:141:4 | ParseFromArray output argument | provenance | MaD:98 |
| protobuf.cpp:143:2:143:4 | *msg | protobuf.cpp:143:23:143:25 | SerializeToArray output argument | provenance | MaD:100 |
| protobuf.cpp:143:23:143:25 | SerializeToArray output argument | protobuf.cpp:144:7:144:10 | * ... | provenance | |
| protobuf.cpp:151:33:151:40 | call to source | protobuf.cpp:152:21:152:31 | *call to data | provenance | TaintFunction |
| protobuf.cpp:152:2:152:4 | ParseFromArray output argument | protobuf.cpp:153:18:153:20 | *msg | provenance | |
| protobuf.cpp:152:21:152:31 | *call to data | protobuf.cpp:152:2:152:4 | ParseFromArray output argument | provenance | MaD:98 |
| protobuf.cpp:153:18:153:20 | *msg | protobuf.cpp:153:22:153:38 | call to SerializeAsString | provenance | MaD:99 |
| protobuf.cpp:153:22:153:38 | call to SerializeAsString | protobuf.cpp:153:22:153:38 | call to SerializeAsString | provenance | |
| protobuf.cpp:153:22:153:38 | call to SerializeAsString | protobuf.cpp:155:22:155:29 | *call to data | provenance | TaintFunction |
| protobuf.cpp:155:2:155:5 | ParseFromArray output argument | protobuf.cpp:157:2:157:5 | *msg2 | provenance | |
| protobuf.cpp:155:22:155:29 | *call to data | protobuf.cpp:155:2:155:5 | ParseFromArray output argument | provenance | MaD:98 |
| protobuf.cpp:157:2:157:5 | *msg2 | protobuf.cpp:157:24:157:26 | SerializeToArray output argument | provenance | MaD:100 |
| protobuf.cpp:157:24:157:26 | SerializeToArray output argument | protobuf.cpp:158:7:158:10 | * ... | provenance | |
| test.cpp:7:47:7:52 | value2 | test.cpp:7:64:7:69 | value2 | provenance | |
| test.cpp:7:64:7:69 | value2 | test.cpp:7:5:7:30 | *ymlStepGenerated_with_body | provenance | |
| test.cpp:10:10:10:18 | call to ymlSource | test.cpp:10:10:10:18 | call to ymlSource | provenance | Src:MaD:48 |
Expand Down Expand Up @@ -532,6 +550,23 @@ nodes
| azure.cpp:295:10:295:20 | contentType | semmle.label | contentType |
| azure.cpp:295:10:295:20 | contentType | semmle.label | contentType |
| azure.cpp:295:10:295:20 | contentType | semmle.label | contentType |
| protobuf.cpp:140:33:140:40 | call to source | semmle.label | call to source |
| protobuf.cpp:141:2:141:4 | ParseFromArray output argument | semmle.label | ParseFromArray output argument |
| protobuf.cpp:141:21:141:31 | *call to data | semmle.label | *call to data |
| protobuf.cpp:143:2:143:4 | *msg | semmle.label | *msg |
| protobuf.cpp:143:23:143:25 | SerializeToArray output argument | semmle.label | SerializeToArray output argument |
| protobuf.cpp:144:7:144:10 | * ... | semmle.label | * ... |
| protobuf.cpp:151:33:151:40 | call to source | semmle.label | call to source |
| protobuf.cpp:152:2:152:4 | ParseFromArray output argument | semmle.label | ParseFromArray output argument |
| protobuf.cpp:152:21:152:31 | *call to data | semmle.label | *call to data |
| protobuf.cpp:153:18:153:20 | *msg | semmle.label | *msg |
| protobuf.cpp:153:22:153:38 | call to SerializeAsString | semmle.label | call to SerializeAsString |
| protobuf.cpp:153:22:153:38 | call to SerializeAsString | semmle.label | call to SerializeAsString |
| protobuf.cpp:155:2:155:5 | ParseFromArray output argument | semmle.label | ParseFromArray output argument |
| protobuf.cpp:155:22:155:29 | *call to data | semmle.label | *call to data |
| protobuf.cpp:157:2:157:5 | *msg2 | semmle.label | *msg2 |
| protobuf.cpp:157:24:157:26 | SerializeToArray output argument | semmle.label | SerializeToArray output argument |
| protobuf.cpp:158:7:158:10 | * ... | semmle.label | * ... |
| test.cpp:7:5:7:30 | *ymlStepGenerated_with_body | semmle.label | *ymlStepGenerated_with_body |
| test.cpp:7:47:7:52 | value2 | semmle.label | value2 |
| test.cpp:7:64:7:69 | value2 | semmle.label | value2 |
Expand Down
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