Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2024-50032

Disclosure Date: October 21, 2024
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

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

rcu/nocb: Fix rcuog wake-up from offline softirq

After a CPU has set itself offline and before it eventually calls
rcutree_report_cpu_dead(), there are still opportunities for callbacks
to be enqueued, for example from a softirq. When that happens on NOCB,
the rcuog wake-up is deferred through an IPI to an online CPU in order
not to call into the scheduler and risk arming the RT-bandwidth after
hrtimers have been migrated out and disabled.

But performing a synchronized IPI from a softirq is buggy as reported in
the following scenario:

    WARNING: CPU: 1 PID: 26 at kernel/smp.c:633 smp_call_function_single
    Modules linked in: rcutorture torture
    CPU: 1 UID: 0 PID: 26 Comm: migration/1 Not tainted 6.11.0-rc1-00012-g9139f93209d1 #1
    Stopper: multi_cpu_stop+0x0/0x320 <- __stop_cpus+0xd0/0x120
    RIP: 0010:smp_call_function_single
    <IRQ>
    swake_up_one_online
    __call_rcu_nocb_wake
    __call_rcu_common
    ? rcu_torture_one_read
    call_timer_fn
    __run_timers
    run_timer_softirq
    handle_softirqs
    irq_exit_rcu
    ? tick_handle_periodic
    sysvec_apic_timer_interrupt
    </IRQ>

Fix this with forcing deferred rcuog wake up through the NOCB timer when
the CPU is offline. The actual wake up will happen from
rcutree_report_cpu_dead().

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CVSS V3 Severity and Metrics
Base Score:
5.5 Medium
Impact Score:
3.6
Exploitability Score:
1.8
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
None
Integrity (I):
None
Availability (A):
High

General Information

Additional Info

Technical Analysis