CVE-2024-47744: KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock
Description
In the Linux kernel, the following vulnerability has been resolved:
KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock
Use a dedicated mutex to guard kvm_usage_count to fix a potential deadlock
on x86 due to a chain of locks and SRCU synchronizations. Translating the
below lockdep splat, CPU1 #6 will wait on CPU0 #1, CPU0 #8 will wait on
CPU2 #3, and CPU2 #7 will wait on CPU1 #4 (if there's a writer, due to the
fairness of r/w semaphores).
CPU0 CPU1 CPU2
1 lock(&kvm->slots_lock);
2 lock(&vcpu->mutex);
3 lock(&kvm->srcu);
4 lock(cpu_hotplug_lock);
5 lock(kvm_lock);
6 lock(&kvm->slots_lock);
7 lock(cpu_hotplug_lock);
8 sync(&kvm->srcu);
Note, there are likely more potential deadlocks in KVM x86, e.g. the same
pattern of taking cpu_hotplug_lock outside of kvm_lock likely exists with
__kvmclock_cpufreq_notifier():
cpuhp_cpufreq_online()
|
-> cpufreq_online()
|
-> cpufreq_gov_performance_limits()
|
-> __cpufreq_driver_target()
|
-> __target_index()
|
-> cpufreq_freq_transition_begin()
|
-> cpufreq_notify_transition()
|
-...
Classification
CVE ID: CVE-2024-47744
Affected Products
Vendor: Linux
Product: Linux
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.03% (probability of being exploited)
EPSS Percentile: 5.54% (scored less or equal to compared to others)
EPSS Date: 2025-05-04 (when was this score calculated)
Stakeholder-Specific Vulnerability Categorization (SSVC)
SSVC Exploitation: none
SSVC Technical Impact: partial
SSVC Automatable: false
References
https://nvd.nist.gov/vuln/detail/CVE-2024-47744https://git.kernel.org/stable/c/4777225ec89f52bb9ca16a33cfb44c189f1b7b47
https://git.kernel.org/stable/c/a2764afce521fd9fd7a5ff6ed52ac2095873128a
https://git.kernel.org/stable/c/760a196e6dcb29580e468b44b5400171dae184d8
https://git.kernel.org/stable/c/44d17459626052a2390457e550a12cb973506b2f