Rust wrapper: check DH::shared_secret buffer size against prime size#10924
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Pull request overview
This PR hardens the Rust DH::shared_secret() wrapper by ensuring the caller-provided output buffer is large enough for the maximum possible DH shared secret (prime-sized), preventing a potential write past the end of the slice due to wc_DhAgree() treating agreeSz as output-only.
Changes:
- Add
DH::prime_size()to query the DH prime (p) size viawc_DhExportParamsRaw()length-only mode. - Reject undersized
doutbuffers inDH::shared_secret()before calling intowc_DhAgree(). - Add Rust tests validating
prime_size()and that undersizedshared_secret()buffers are rejected without overwriting adjacent memory.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
| wrapper/rust/wolfssl-wolfcrypt/src/dh.rs | Adds prime_size() and uses it to preflight shared_secret() output buffer length. |
| wrapper/rust/wolfssl-wolfcrypt/tests/test_dh.rs | Adds tests for prime size and for rejecting undersized shared-secret output buffers. |
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The underlying C API treats the agreeSz parameter as output-only.
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|
retest this please (build removed) |
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|
retest this please (ERROR: Build 'PRB-fips-ready-config' failed with result: ABORTED) |
JacobBarthelmeh
approved these changes
Jul 16, 2026
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Description
Rust wrapper: check DH::shared_secret buffer size against prime size
The underlying C API treats the agreeSz parameter as output-only.
Fixes ZD#22155
Testing
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