Bug 2507175 (CVE-2026-64288)

Summary: CVE-2026-64288 kernel: KVM: arm64: nv: Avoid dereferencing NULL VNCR pseudo-TLB
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the kernel's Kernel-based Virtual Machine (KVM) component for ARM64 architectures. A race condition can occur during the invalidation of the virtual Nested Translation Cache (VNCR pseudo-TLB) when a virtual CPU (vcpu) is being brought online or offline. This can lead to a null pointer dereference, which could cause the system to crash, resulting in a denial of service.
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Description OSIDB Bzimport 2026-07-25 10:08:59 UTC 
In the Linux kernel, the following vulnerability has been resolved:

KVM: arm64: nv: Avoid dereferencing NULL VNCR pseudo-TLB

VNCR TLB invalidation occurs from MMU notifiers or TLBI instructions,
and either can race against a vcpu not being onlined yet (no pseudo-TLB
allocated). Similarly, the TLB might be invalid, and the invalidation
should be skipped in this case.

Both kvm_invalidate_vncr_ipa() and kvm_invalidate_vncr_va() are
expected to perform the same checks, except that the latter doesn't
check for the allocation and blindly dereferences the pointer.

Solve this by introducing a new iterator built on top of the usual
kvm_for_each_vcpu() that checks for both of the above conditions,
and convert the two users to it.
Comment 1 TEJ RATHI 2026-07-29 13:54:01 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072503-CVE-2026-64288-c17b@gregkh/T