Linux Kernel up to 6.0.7 KVM kvm_gpc_check use after free

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.0.7 and classified as critical. The affected element is the function kvm_gpc_check of the component KVM. Performing a manipulation results in use after free. This vulnerability is cataloged as CVE-2022-49882. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.0.7. This affects the function kvm_gpc_check of the component KVM. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: KVM: Reject attempts to consume or refresh inactive gfn_to_pfn_cache Reject kvm_gpc_check() and kvm_gpc_refresh() if the cache is inactive. Not checking the active flag during refresh is particularly egregious, as KVM can end up with a valid, inactive cache, which can lead to a variety of use-after-free bugs, e.g. consuming a NULL kernel pointer or missing an mmu_notifier invalidation due to the cache not being on the list of gfns to invalidate. Note, "active" needs to be set if and only if the cache is on the list of caches, i.e. is reachable via mmu_notifier events. If a relevant mmu_notifier event occurs while the cache is "active" but not on the list, KVM will not acquire the cache's lock and so will not serailize the mmu_notifier event with active users and/or kvm_gpc_refresh(). A race between KVM_XEN_ATTR_TYPE_SHARED_INFO and KVM_XEN_HVM_EVTCHN_SEND can be exploited to trigger the bug. 1. Deactivate shinfo cache: kvm_xen_hvm_set_attr case KVM_XEN_ATTR_TYPE_SHARED_INFO kvm_gpc_deactivate kvm_gpc_unmap gpc->valid = false gpc->khva = NULL gpc->active = false Result: active = false, valid = false 2. Cause cache refresh: kvm_arch_vm_ioctl case KVM_XEN_HVM_EVTCHN_SEND kvm_xen_hvm_evtchn_send kvm_xen_set_evtchn kvm_xen_set_evtchn_fast kvm_gpc_check return -EWOULDBLOCK because !gpc->valid kvm_xen_set_evtchn_fast return -EWOULDBLOCK kvm_gpc_refresh hva_to_pfn_retry gpc->valid = true gpc->khva = not NULL Result: active = false, valid = true 3. Race ioctl KVM_XEN_HVM_EVTCHN_SEND against ioctl KVM_XEN_ATTR_TYPE_SHARED_INFO: kvm_arch_vm_ioctl case KVM_XEN_HVM_EVTCHN_SEND kvm_xen_hvm_evtchn_send kvm_xen_set_evtchn kvm_xen_set_evtchn_fast read_lock gpc->lock kvm_xen_hvm_set_attr case KVM_XEN_ATTR_TYPE_SHARED_INFO mutex_lock kvm->lock kvm_xen_shared_info_init kvm_gpc_activate gpc->khva = NULL kvm_gpc_check [ Check passes because gpc->valid is still true, even though gpc->khva is already NULL. ] shinfo = gpc->khva pending_bits = shinfo->evtchn_pending CRASH: test_and_set_bit(..., pending_bits)

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2022-49882 since 05/01/2025. The exploitability is told to be easy. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 03/15/2026).

Upgrading to version 6.0.8 eliminates this vulnerability. Applying the patch bfa9672f8fc9eb118124bab61899d2dd497f95ba/ecbcf030b45666ad11bc98565e71dfbcb7be4393 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2025-0922). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Dell Avamar
• Open Source Linux Kernel
• IBM DataPower Gateway
• Dell NetWorker
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.0.0
• 6.0.1
• 6.0.2
• 6.0.3
• 6.0.4
• 6.0.5
• 6.0.6
• 6.0.7

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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