{ "number": 36534, "input_hash": "10b0cd95d061d240", "model": "ledger", "prompt_hash": null, "created": "2026-11-02T01:11:44+00:00", "result": { "summary": "Move compiler and linker hardening flags into a dedicated CMake interface library (`hardening_interface`) linked by `core_interface`, and pass those flags down to the secp256k1 subtree build.", "problem": "The secp256k1 subtree does not inherit flags from `core_interface`, so its objects are built without hardening flags such as FORTIFY, stack protection, stack clash protection, and branch/control-flow protection unless compiler defaults provide them. Because linkers drop binary-wide control-flow protection markers (like AArch64 BTI/PAC/GCS or x86_64 CET) if any linked object lacks them, the unhardened secp256k1 objects cause the final executable to lose hardware control-flow protections.", "card": "This pull request passes Bitcoin Core's compiler and linker hardening flags to the embedded libsecp256k1 subtree build by re-introducing a `hardening_interface` CMake target. Previously, secp256k1 objects were built without flags like stack protection and branch protection. Because linkers drop binary-wide control-flow integrity flags if even a single linked object lacks them, secp256k1 objects stripped control-flow markers from release binaries on toolchains that do not enable them by default. Testing on Ubuntu 26.04 with GCC 15 confirms this change restores the `AArch64 feature: BTI, PAC, GCS` elf note on bitcoind.", "evidence": [ "Author notes: 'On aarch64 Ubuntu 26.04 with GCC 15 this also costs the whole binary its control flow property: master\\'s bitcoind has no AArch64 feature note, and the three secp256k1 objects are the only ones in the build tree without it.'", "Author verifies: 'With it, the same build shows AArch64 feature: BTI, PAC, GCS on bitcoind.'" ], "scope_notes": "Small build-system change reverting commit 77e553ab6a to re-introduce `hardening_interface` and forward its options to `cmake/secp256k1.cmake`.", "changed_since_previous": "Diff provided; the implementation matches the previous description.", "thread": { "last_event_at": "2026-11-01T18:50:06Z", "events": 2, "head_sha": "08bd06ccd488d5a40b1b29b0a3052663668c8f52", "schema_floor": 2, "schema": 2 }, "waiting_on": [ { "at": "2026-11-01", "id": "c:6562328475", "on": "reviewer", "url": "https://github.com/bitcoin/bitcoin/pull/36534#issuecomment-6562328475", "what": "hebasto to review the update in 08bd06ccd4 addressing Ralph's feedback" }, { "at": "2026-11-01", "id": "c:6562328475", "on": "reviewer", "url": "https://github.com/bitcoin/bitcoin/pull/36534#issuecomment-6562328475", "what": "hebasto to check the update addressing Ralph's feedback" } ], "risk": { "level": "medium", "touches": [ "build" ], "why": "Passing additional compiler and linker flags to libsecp256k1 could cause build failures on esoteric platforms or toolchain configurations." }, "discussion": { "author_status": "last statement processed 2026-11-01", "open_concerns": [], "resolved_concerns": [ "hebasto: address Ralph's feedback (fixed by fametrano 2026-11-01)" ] }, "reviewability": { "state": "Ready", "label": "Ready", "reason": "Nothing known that would invalidate a review now." }, "agreement": { "state": "Crickets", "summary": "Crickets: no substantive comment either way", "reason": "Initial record. hebasto asked that Ralph's feedback be addressed; fametrano pushed commit 08bd06ccd4 to check hardening flags with the C compiler and replied. / Initial record. hebasto noted that Ralph's feedback should be addressed; fametrano pushed an update addressing it.", "evidence": [], "objections": [ { "reviewer": "hebasto", "association": "MEMBER", "type": "suggestion", "kind": "approach", "harm": "", "request": "address Ralph's feedback", "question": "", "text": "address Ralph's feedback", "clears_with": "answer", "blocking": false, "status": "fixed", "status_note": "author pushed commit 08bd06ccd4 checking hardening flags with the C compiler", "cleared": true, "author_replied": true, "others_replied": false, "fix_pushed": true, "replies": [ "c:6562328475" ], "evidence": "2026-10-27: 'I think that Ralph's feedback should be addressed.'", "url": "https://github.com/bitcoin/bitcoin/pull/36534#issuecomment-6444090309", "id": "c:6444090309", "at": "2026-10-27", "status_at": "2026-11-01", "status_by": "fametrano", "resolution_evidence": "2026-11-01: fametrano: 'Ralph's finding is addressed in 08bd06ccd4'", "pin": null, "from_schema": 2 } ], "support": [], "participants": [ { "login": "hebasto", "stance": "neutral", "note": "asked to address Ralph's feedback", "association": "MEMBER", "comments": 1, "first": "2026-10-27", "last": "2026-10-27" } ], "derivation": "no substantive comment either way", "model_state": null, "corrections": [], "notes": "Initial record. hebasto asked that Ralph's feedback be addressed; fametrano pushed commit 08bd06ccd4 to check hardening flags with the C compiler and replied. / Initial record. hebasto noted that Ralph's feedback should be addressed; fametrano pushed an update addressing it." }, "dependencies": { "depends_on": [], "enables": [] }, "categories": [ { "name": "build", "member": true, "evidence": "Carries the 'Build system' label and modifies CMakeLists.txt and cmake/secp256k1.cmake to manage compiler flags passed to secp256k1.", "band": "P2", "reason_tag": "bug fix", "score": 0.7, "factors": { "bug_severity": 2, "leverage": 0, "performance": 0, "security_stability": 2, "user_value": 0 }, "rationale": "Fixes a regression where secp256k1 objects omit hardening flags, causing linkers to drop binary-wide hardware control-flow protections (like AArch64 BTI/PAC/GCS or x86_64 CET) from bitcoind. As the author notes, 'the unhardened secp256k1 objects cause the final executable to lose hardware control-flow protections' on master." } ], "confidence": "high", "uncertainties": [], "needs": [] }, "cost_usd": 0.0, "source": { "record": "2026-11-02T01:11:44+00:00", "code": "2026-10-17T01:21:25+00:00", "judgments": 1 } }