Описание
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.
A flaw was found in the Linux kernel's tracing subsystem. A local user with access to the tracing interface can cause a Denial of Service (DoS) due to a race condition when attaching histogram triggers to filtered events. Under specific timing conditions, buffered trace events are processed without expected reservation tracking, triggering an internal kernel warning that can halt the system if configured to panic on warnings, as well as produce inaccurate timestamps.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel | Fix deferred | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-8 | Not affected | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-9 | Fix deferred |
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Дополнительная информация
Статус:
EPSS
1.9 Low
CVSS3
Связанные уязвимости
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_b...
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' > \
In the Linux kernel, the following vulnerability has been resolved: t ...
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' > \ ...
EPSS
1.9 Low
CVSS3