myxce/.wolf/bugs/bug-1769.md
Rongsong Shen d26ff8870d
feat(buglog): one Markdown record per bug, checked against a record standard
The buglog was one 27K-line JSON file whose fields covered only symptom,
root cause and fix, as free text: 2% of entries named the code version a
bug was found on, 12% the build profile, 36% a way to reproduce, and 58% of
the file was OpenWolf hook auto-detections ("Missing guard clause",
"Function not marked async" on .md files).

- .claude/skills/buglog/bug-record.md: the record standard. Eight
  sections (Summary as the title, Description, Environment, Reproduction;
  Root cause, Fix, Verification, References once fixed), each with the
  content it must contain -- e.g. Environment needs the OS, the libc the
  failing binary loads (from its ELF interpreter: glibc 2.42 in the nix
  shell vs 2.40 on the host), toolchain, build profile and commit.
- .wolf/bugs/<id>.md: 500 records migrated from buglog.json; every field
  verified to round-trip. They carry legacy: true and an explicit "not
  recorded" where the old log had no such field; component derived from
  file paths, severity from keywords (else unknown), fix_commits from
  hashes in status_note/fix that git resolves (91 of 463 fixed).
- .wolf/buglog-archive.json: the 710 hook auto-detections, verbatim.
- .wolf/buglog.json is now an index generated from the records, keeping
  the fields OpenWolf's hooks and `openwolf bug search` read.
- scripts/buglog.py rewritten: new (template + Environment collected from
  the machine and --binary), check, status (refuses a status the record
  doesn't support; fixed needs Root cause, Fix, Verification and
  --commit hashes git resolves), note, recur, set, show, list, triage,
  env, index. 29 unittest cases in scripts/tests/test_buglog.py.
- scripts/git-hooks/pre-commit runs `check --staged`: incomplete staged
  records, a legacy record hand-changed to fixed without the fix-time
  sections, a new record claiming legacy: true, or a stale index refuse
  the commit.
- scripts/gitea-sync.py reads the records: issue body = the record's
  sections plus linked fix commits (origin remote, GITEA_COMMIT_REPO to
  override), and a body hash so an issue's text is refreshed when the
  record changes.
- bug-1866 rewritten to the full standard as the worked example.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-28 03:40:11 +00:00

39 lines
3.2 KiB
Markdown

---
id: "bug-1769"
status: "fixed"
status_updated: "2026-09-25"
status_note: "1ecd348f"
component: "scheduler"
severity: "crash"
timestamp: "2026-09-04T00:00:00Z"
last_seen: "2026-09-19T09:00:00Z"
occurrences: 1
files: []
tags: ["scheduler", "alter-resreq", "type-confusion", "heap-oob-read", "pre-existing", "severity-high", "untested", "scheduler-allocation-discovery"]
related: ["bug-1768"]
fix_commits: ["1ecd348f"]
legacy: true
---
# bug-1769: out-of-scope type confusion discovered during scheduler-allocation task 5.1's review…
## Description
OPEN, NOT A CRASH (but reachable) -- pre-existing, out-of-scope type confusion discovered during scheduler-allocation task 5.1's review (cache/dispatch wiring). core_build_alter_schedobj() (src/scheduler/src/core_events.c) stores raw `xce_compound_schedobj_t*` (sizeof == 24 bytes) into `obj->u.alters` (an xlist_t), but sched_make_alter_allocation() (src/scheduler/src/scheduler.c) reads each entry back cast as `xce_sched_obj_t*` (sizeof == 176 bytes, with `offsetof(xce_sched_obj_t, u) == 136`) and dereferences `obj->u.compound->resreq` through that mis-typed pointer.
## Environment
_Not recorded (migrated from buglog.json)._
## Reproduction
_Not recorded (migrated from buglog.json)._
## Root cause
CONFIRMED via direct code read at both the construction site (core_events.c) and the read site (scheduler.c), plus a compiled offsetof/sizeof probe against the real headers during task 5.1's review: this is a genuine struct-layout mismatch, not a false alarm -- the two types do not share a compatible prefix layout. Any real ALTER-tagged job (the resreq grammar's `{A} || {B}` alternate syntax legitimately produces XCE_RESREQ_ALTER per xce_resreq.peg) dereferencing through this cast reads ~112 bytes past the actual 24-byte allocation, an out-of-bounds heap read. Separately confirmed during the same investigation that test_snapshot_load_allocator_regression.c's header comment claiming to already exercise this ALTER path is itself mistaken: its `"type == any"` fixture has no `{`/`}` braces, so per xce_resreq.peg's grammar it parses as XCE_RESREQ_PRIMARY, not ALTER -- it never actually drives sched_make_alter_allocation()'s u.alters read path. No test anywhere in the tree currently constructs a real multi-entry u.alters list and drives it through sched_make_alter_allocation(), so this defect is both real and currently completely untested.
## Fix
NOT FIXED -- discovered and characterized during scheduler-allocation task 5.1's independent review (2026-09-04); deliberately left out of that task's scheduler.c-dispatch boundary. Needs a dedicated bugfix task: either change core_build_alter_schedobj() to store properly-typed xce_sched_obj_t* entries into u.alters (matching what sched_make_alter_allocation() expects), or change sched_make_alter_allocation() to read xce_compound_schedobj_t* entries directly without the intermediate xce_sched_obj_t* cast. Should be paired with a new regression test that actually constructs an ALTER-tagged job (real `{A}||{B}` resreq syntax) and drives it end to end, since the existing test that was believed to cover this does not.
## Verification
_Not recorded (migrated from buglog.json)._
## References
- Related: bug-1768