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Race Condition Affecting openshift/ose-rhel-coreos-9 package, versions *

Severity

 Recommended
0.0
low
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.17% (7th percentile)

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  • Snyk IDSNYK-RHEL9-OPENSHIFTOSERHELCOREOS9-21897893
  • published30 Oct 2026
  • disclosed28 Oct 2026
Report a new vulnerability Found a mistake?

Introduced: 28 Oct 2026

NewCVE-2026-99140  (opens in a new tab)
CWE-366  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 openshift/ose-rhel-coreos-9.

NVD Description

Note: Versions mentioned in the description apply only to the upstream openshift/ose-rhel-coreos-9 package and not the openshift/ose-rhel-coreos-9 package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

tracing: Fix hist trigger timestamps for buffered events

Syzkaller triggered a WARN_ON_ONCE(!nest) warning:

WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp Call trace: ring_buffer_event_time_stamp hist_field_timestamp hist_fn_call event_hist_trigger event_triggers_call __event_trigger_test_discard trace_event_buffer_commit do_trace_event_raw_event_sched_switch trace_event_raw_event_sched_switch

The warning is probabilistically reproducible and is related to syzkaller executing the following commands:

echo 'prev_pid == 999999' > events/sched/sched_switch/filter echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger

The specific triggering process is as follows:

CPU 0 CPU 1 (context switching) (echo 'hist:keys=common_timestamp' >
events/sched/sched_switch/trigger) do_trace_event_raw_event_##call trace_event_buffer_lock_reserve if (!tr->no_filter_buffering_ref && trace_file->flags & EVENT_FILE_FL_FILTERED) return entry; // return directly event_hist_trigger_parse hist_register_trigger tracing_set_filter_buffering(file->tr, true); tr->no_filter_buffering_ref++; __trace_buffer_lock_reserve rb_start_commit local_inc(&cpu_buffer->committing); // skipped and not executed trace_event_buffer_commit __event_trigger_test_discard event_triggers_call event_hist_trigger hist_fn_call hist_field_timestamp ring_buffer_event_time_stamp nest = local_read(&cpu_buffer->committing); WARN_ON_ONCE(!nest) // trigger warning

The root cause is that when an event file has a filter attached and the hist trigger has not yet been attached, trace_event_buffer_lock_reserve() writes the event into the per-CPU trace_buffered_event temp buffer instead of reserving it in the ring buffer, so cpu_buffer->committing is not incremented. When the event is later processed at commit time by a hist trigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a zero committing count, triggering WARN_ON_ONCE(!nest).

tracing_event_time_stamp() was added by commit d8279bfc5e959 ("tracing: Add tracing_event_time_stamp() API") for exactly this case: if the event is the per-CPU trace_buffered_event, it returns the current ring buffer timestamp. But it never gained a caller. Use it in hist_field_timestamp(), so that a hist trigger that races onto a buffered event records the current time, which is only marginally later than when the event was recorded, instead of warning and recording a bogus timestamp.

CVSS Base Scores

version 3.1