CVE-2026-46147

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

KVM: arm64: Fix pin leak and publication ordering in __pkvm_init_vcpu()

Two bugs exist in the vCPU initialisation path:

1. If a check fails after hyp_pin_shared_mem() succeeds, the cleanup path jumps to unlock without calling unpin_host_vcpu() or unpin_host_sve_state(), permanently leaking pin references on the host vCPU and SVE state pages.

   Extract a register_hyp_vcpu() helper that performs the checks and the store. When register_hyp_vcpu() returns an error, call unpin_host_vcpu() and unpin_host_sve_state() inline before falling through to the existing unlock label.

2. register_hyp_vcpu() publishes the new vCPU pointer into hyp_vm->vcpus[] with a bare store, allowing a concurrent caller of pkvm_load_hyp_vcpu() to observe a partially initialised vCPU object.

   Ensure the store uses smp_store_release() and the load uses smp_load_acquire(). While vm_table_lock currently serialises the store and the load, these barriers ensure the reader sees the fully initialised hyp_vcpu object even if there were a lockless path or if the locks own ordering guarantees were insufficient for nested object initialization.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/6d69c0ed978f7f0efd053fc98390f25ab77c1aea
• https://git.kernel.org/stable/c/73b9c1e5da84cd69b1a86e374e450817cd051371
• https://git.kernel.org/stable/c/7d3c27b54253cda91dc4d2c1bfc109c490837ab9