Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
firmware: arm_sdei: Fix sleep from invalid context BUG
Running a preempt-rt (v6.2-rc3-rt1) based kernel on an Ampere Altra triggers:
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 24, name: cpuhp/0
preempt_count: 0, expected: 0
RCU nest depth: 0, expected: 0
3 locks held by cpuhp/0/24:
#0: ffffda30217c70d0 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x5c/0x248
#1: ffffda30217c7120 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x5c/0x248
#2: ffffda3021c711f0 (sdei_list_lock){….}-{3:3}, at: sdei_cpuhp_up+0x3c/0x130
irq event stamp: 36
hardirqs last enabled at (35): [
sdei_cpuhp_up() is called in the STARTING hotplug section, which runs with interrupts disabled. Use a CPUHP_AP_ONLINE_DYN entry instead to execute the cpuhp cb later, with preemption enabled.
SDEI originally got its own cpuhp slot to allow interacting with perf. It got superseded by pNMI and this early slot is not relevant anymore. 1
Some SDEI calls (e.g. SDEI_1_0_FN_SDEI_PE_MASK) take actions on the calling CPU. It is checked that preemption is disabled for them. _ONLINE cpuhp cb are executed in the ‘per CPU hotplug thread’. Preemption is enabled in those threads, but their cpumask is limited to 1 CPU. Move ‘WARN_ON_ONCE(preemptible())’ statements so that SDEI cpuhp cb don’t trigger them.
Also add a check for the SDEI_1_0_FN_SDEI_PRIVATE_RESET SDEI call which acts on the calling CPU.
Details
- Affected product:
- AlmaLinux 9.2 ESU , TuxCare 9.6 ESU
- Affected packages:
- kernel @ 5.14.0 (+1 more)
In the Linux kernel, the following vulnerability has been resolved:
firmware: arm_sdei: Fix sleep from invalid context BUG
Running a preempt-rt (v6.2-rc3-rt1) based kernel on an Ampere Altra triggers:
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
in_atomic(): 0, irqs_disabled(): 128, non_block: 0, pid: 24, name: cpuhp/0
preempt_count: 0, expected: 0
RCU nest depth: 0, expected: 0
3 locks held by cpuhp/0/24:
#0: ffffda30217c70d0 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x5c/0x248
#1: ffffda30217c7120 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x5c/0x248
#2: ffffda3021c711f0 (sdei_list_lock){….}-{3:3}, at: sdei_cpuhp_up+0x3c/0x130
irq event stamp: 36
hardirqs last enabled at (35): [
sdei_cpuhp_up() is called in the STARTING hotplug section, which runs with interrupts disabled. Use a CPUHP_AP_ONLINE_DYN entry instead to execute the cpuhp cb later, with preemption enabled.
SDEI originally got its own cpuhp slot to allow interacting with perf. It got superseded by pNMI and this early slot is not relevant anymore. 1
Some SDEI calls (e.g. SDEI_1_0_FN_SDEI_PE_MASK) take actions on the calling CPU. It is checked that preemption is disabled for them. _ONLINE cpuhp cb are executed in the ‘per CPU hotplug thread’. Preemption is enabled in those threads, but their cpumask is limited to 1 CPU. Move ‘WARN_ON_ONCE(preemptible())’ statements so that SDEI cpuhp cb don’t trigger them.
Also add a check for the SDEI_1_0_FN_SDEI_PRIVATE_RESET SDEI call which acts on the calling CPU.