Commit 7c305d51 authored by Mathias Krause's avatar Mathias Krause Committed by Sean Christopherson
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KVM: x86: Limit check IDs for KVM_SET_BOOT_CPU_ID 



Do not accept IDs which are definitely invalid by limit checking the
passed value against KVM_MAX_VCPU_IDS and 'max_vcpu_ids' if it was
already set.

This ensures invalid values, especially on 64-bit systems, don't go
unnoticed and lead to a valid id by chance when truncated by the final
assignment.

Fixes: 73880c80 ("KVM: Break dependency between vcpu index in vcpus array and vcpu_id.")
Signed-off-by: default avatarMathias Krause <minipli@grsecurity.net>
Link: https://lore.kernel.org/r/20240614202859.3597745-3-minipli@grsecurity.net


Co-developed-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 8b8e57e5

arch/x86/kvm/x86.c

+3 −0
Original line number Diff line number Diff line
@@ -7228,6 +7228,9 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) 
		mutex_lock(&kvm->lock);

		if (kvm->created_vcpus)

			r = -EBUSY;

		else if (arg > KVM_MAX_VCPU_IDS ||

			 (kvm->arch.max_vcpu_ids && arg > kvm->arch.max_vcpu_ids))

			r = -EINVAL;

		else

			kvm->arch.bsp_vcpu_id = arg;

		mutex_unlock(&kvm->lock);