ALSA: pcm: Disable bottom softirqs as part of spin_lock_irq() on PREEMPT_RT
In the Linux kernel, the following vulnerability has been resolved:
ALSA: pcm: Disable bottom softirqs as part of spin_lock_irq() on PREEMPT_RT
snd_pcm_group_lock_irq() acquires a spinlock_t and disables interrupts
via spin_lock_irq(). This also implicitly disables the handling of
softirqs such as TIMER_SOFTIRQ.
On PREEMPT_RT softirqs are preemptible and spin_lock_irq() does not
disable them. That means a timer can be invoked during spin_lock_irq()
on the same CPU. Due to synchronisations reasons local_bh_disable() has
a per-CPU lock named softirq_ctrl.lock which synchronizes individual
softirq against each other.
syz-bot managed to trigger a lockdep report where softirq_ctrl.lock is
acquired in hrtimer_cancel() in addition to hrtimer_run_softirq(). This
is a possible deadlock.
The softirq_ctrl.lock can not be made part of spin_lock_irq() as this
would lead to too much synchronisation against individual threads on the
system. To avoid the possible deadlock, softirqs must be manually
disabled before the lock is acquired.
Disable softirqs before the lock is acquired on PREEMPT_RT.
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)
2025-11-12
–
–
–
–
0.02%
2025-11-21
–
–
–
–
0.02%
2025-12-14
–
–
–
–
0.02%
2026-01-19
–
–
–
–
0.03%
2026-02-22
–
–
–
–
0.03%
2026-03-08
–
–
–
–
0.03%
2026-03-15
–
–
–
–
0.03%
2026-04-12
–
–
–
–
0.02%
2026-04-26
–
–
–
–
0.02%
2026-06-14
–
–
–
–
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.