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CVE-2022-48943

HIGHCVSS 7.8/10EPSS 0.24%

Last modified

CVE-2022-48943 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: make apf token non-zero to fix bug In current async pagefault logic, when a page is ready, KVM relies on kvm_arch_can_dequeue_async_page_present() to determine whether to deliver a READY event to the Guest. This function test token value of struct kvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a READY event is finished by Guest. EPSS estimates a 0.24% chance of exploitation in the next 30 days.

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: make apf token non-zero to fix bug In current async pagefault logic, when a page is ready, KVM relies on kvm_arch_can_dequeue_async_page_present() to determine whether to deliver a READY event to the Guest. This function test token value of struct kvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a READY event is finished by Guest. If value is zero meaning that a READY event is done, so the KVM can deliver another. But the kvm_arch_setup_async_pf() may produce a valid token with zero value, which is confused with previous mention and may lead the loss of this READY event. This bug may cause task blocked forever in Guest: INFO: task stress:7532 blocked for more than 1254 seconds. Not tainted 5.10.0 #16 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:stress state:D stack: 0 pid: 7532 ppid: 1409 flags:0x00000080 Call Trace: __schedule+0x1e7/0x650 schedule+0x46/0xb0 kvm_async_pf_task_wait_schedule+0xad/0xe0 ? exit_to_user_mode_prepare+0x60/0x70 __kvm_handle_async_pf+0x4f/0xb0 ? asm_exc_page_fault+0x8/0x30 exc_page_fault+0x6f/0x110 ? asm_exc_page_fault+0x8/0x30 asm_exc_page_fault+0x1e/0x30 RIP: 0033:0x402d00 RSP: 002b:00007ffd31912500 EFLAGS: 00010206 RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0 RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0 RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086 R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000 R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000

Metrics

CVSS 3.1
7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
0.24%

15.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

VendorProductVersions
LinuxLinux Kernel< 5.10.103
LinuxLinux Kernel>= 5.11, < 5.15.26
LinuxLinux Kernel>= 5.16, < 5.16.12

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2022-48943?
In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: make apf token non-zero to fix bug In current async pagefault logic, when a page is ready, KVM relies on kvm_arch_can_dequeue_async_page_present() to determine whether to deliver a READY event to the Guest. This function test token value of struct kvm_vcpu_pv_apf_data, which must be reset to zero by Guest kernel when a READY event is finished by Guest. If value is zero meaning that a READY event is done, so the KVM can deliver another. But the kvm_arch_setup_async_pf() may produce a valid token with zero value, which is confused with previous mention and may lead the loss of this READY event. This bug may cause task blocked forever in Guest: INFO: task stress:7532 blocked for more than 1254 seconds. Not tainted 5.10.0 #16 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:stress state:D stack: 0 pid: 7532 ppid: 1409 flags:0x00000080 Call Trace: __schedule+0x1e7/0x650 schedule+0x46/0xb0 kvm_async_pf_task_wait_schedule+0xad/0xe0 ? exit_to_user_mode_prepare+0x60/0x70 __kvm_handle_async_pf+0x4f/0xb0 ? asm_exc_page_fault+0x8/0x30 exc_page_fault+0x6f/0x110 ? asm_exc_page_fault+0x8/0x30 asm_exc_page_fault+0x1e/0x30 RIP: 0033:0x402d00 RSP: 002b:00007ffd31912500 EFLAGS: 00010206 RAX: 0000000000071000 RBX: ffffffffffffffff RCX: 00000000021a32b0 RDX: 000000000007d011 RSI: 000000000007d000 RDI: 00000000021262b0 RBP: 00000000021262b0 R08: 0000000000000003 R09: 0000000000000086 R10: 00000000000000eb R11: 00007fefbdf2baa0 R12: 0000000000000000 R13: 0000000000000002 R14: 000000000007d000 R15: 0000000000001000
How severe is CVE-2022-48943?
CVE-2022-48943 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.
How do I fix CVE-2022-48943?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST