perf/x86: Fix NULL event access and potential PEBS record loss
In the Linux kernel, the following vulnerability has been resolved:
perf/x86: Fix NULL event access and potential PEBS record loss
When intel_pmu_drain_pebs_icl() is called to drain PEBS records, the
perf_event_overflow() could be called to process the last PEBS record.
While perf_event_overflow() could trigger the interrupt throttle and
stop all events of the group, like what the below call-chain shows.
perf_event_overflow()
-> __perf_event_overflow()
->__perf_event_account_interrupt()
-> perf_event_throttle_group()
-> perf_event_throttle()
-> event->pmu->stop()
-> x86_pmu_stop()
The side effect of stopping the events is that all corresponding event
pointers in cpuc->events[] array are cleared to NULL.
Assume there are two PEBS events (event a and event b) in a group. When
intel_pmu_drain_pebs_icl() calls perf_event_overflow() to process the
last PEBS record of PEBS event a, interrupt throttle is triggered and
all pointers of event a and event b are cleared to NULL. Then
intel_pmu_drain_pebs_icl() tries to process the last PEBS record of
event b and encounters NULL pointer access.
To avoid this issue, move cpuc->events[] clearing from x86_pmu_stop()
to x86_pmu_del(). It's safe since cpuc->active_mask or
cpuc->pebs_enabled is always checked before access the event pointer
from cpuc->events[].
CVE 정보
EPSS
EPSS는 취약점이 악용될 가능성을 예측하는 점수 모델입니다.
EPSS 점수
EPSS 모델은 0과 1(0~100%) 사이의 확률 점수를 생성합니다. 점수가 높을수록 취약점이 악용될 가능성이 높습니다.
날짜
EPSS V0
EPSS V1
EPSS V2 (> 2022-02-04)
EPSS V3 (> 2025-03-07)
EPSS V4 (> 2025-03-17)
2025-12-24
–
–
–
–
0.02%
2025-12-30
–
–
–
–
0.02%
2026-01-25
–
–
–
–
0.02%
2026-03-08
–
–
–
–
0.03%
2026-03-22
–
–
–
–
0.03%
2026-04-26
–
–
–
–
0.03%
2026-05-17
–
–
–
–
0.03%
2026-05-31
–
–
–
–
0.02%
2026-06-07
–
–
–
–
0.03%
EPSS 백분위수
백분위수는 EPSS 점수에 따라 CVE의 순위를 매기는 데 사용됩니다. 예를 들어 EPSS 점수 기준 95번째 백분위수의 CVE는 다른 CVE의 95%보다 악용될 가능성이 높습니다.