3.2 KiB
| id | status | status_updated | status_note | component | severity | timestamp | last_seen | occurrences | files | tags | related | repro_attempts | gitea_issue | gitea_synced_status | gitea_synced_hash | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| bug-1956 | cannot-reproduce | 2026-10-10 | no NULL path from the wire; the explicit NULL branch in job_start_local_task is unreachable through decoding | worker | crash | 2026-10-10T08:46:13Z | 2026-10-10T08:46:13Z | 1 |
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decoder analysis 2026-10-10: empty launchType decodes to "" (capn_val0 default + strdup), never NULL | 387 | cannot-reproduce | 46653c4397e0 |
bug-1956: xcecd compares a NULL launch_type with strcmp when a job has no launch type (possible crash)
Description
Observed: (source reading, 2026-10-10; suspected, not reproduced)
job_start_local_task() stores NULL when the start info has no launch type
and then dereferences it:
if (d->start_info->launch_type) {
job_ctx->startinfo->launch_type = strdup(...);
} else {
job_ctx->startinfo->launch_type = NULL; /* :981-985 */
}
...
if (strcmp(job_ctx->startinfo->launch_type, "openmpi") == 0 /* :994 */
job_start_remote_task() does the same without a check (:753). The apiserver
sends no launch type when the user gives none (cStringOrNil,
backend/convert.go:339). Jobs without a launch type do run in existing
tests, so the decoder may deliver an empty string rather than NULL: not
confirmed either way.
Expected: a missing launch type means a plain (non-MPI) job; no NULL dereference. Impact: possible worker crash at job start for jobs without a launch type. Found by: review of the bug-1940/1942 fixes, 2026-10-10.
UPDATE (2026-10-10): Not confirmed: the generated decoder reads launchType with capn_get_text(..., capn_val0) whose default is {0,"",0} and then STRING_DUPs (strdup) it (src/xce.build/lib/controller.capnp.c:6398), so a job start without a launch type reaches the worker as "" (non-NULL); strcmp at controller_connector.c:753/994 is safe. job_start_local_task's explicit NULL assignment (:985) is only reachable if start_info->launch_type is NULL, which decoding never produces.
Environment
- OS: no /etc/os-release; Docker container; NixOS kernel; kernel Linux 6.18.33 x86_64
- libc: glibc 2.42-47 (interpreter /nix/store/wb6rhpznjfczwlwx23zmdrrw74bayxw4-glibc-2.42-47/lib/ld-linux-x86-64.so.2)
- Toolchain: gcc (GCC) 15.2.0, meson 1.9.1
- Build: asan (xce.build)
- Code: scheduler-framework @ 8568c8ab-dirty
- Deployment: real
xcecdworker (systemd/dbus); multi-host for the remote-task case
Reproduction
- Decode a job start message whose start info has no launch type and run
job_start_local_task()(worker unit test), or submit a job without a launch type through libxce/harness to a realxcecd. - Check whether
startinfo->launch_typeis NULL at:994.
- Frequency: deterministic by code reading (not yet run)
- Evidence: the code quoted in Description; no logs kept.
Root cause
TODO: required for fixed/partial
Fix
TODO: required for fixed/partial
Verification
- Test: TODO: name + file; RED before the fix, GREEN after
- Suites: TODO: suite results and build profile
- Live: TODO: soak/deploy run, or n/a and why
References
- Related: none