linux-kernel - Re: [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty

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Date:   Tue, 24 Dec 2019 13:19:30 -0500
From:   Peter Xu <peterx@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     James Hogan <jhogan@...nel.org>,
        Paul Mackerras <paulus@...abs.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Wanpeng Li <wanpengli@...cent.com>,
        Philippe Mathieu-Daudé <f4bug@...at.org>,
        kvm@...r.kernel.org, David Hildenbrand <david@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Cornelia Huck <cohuck@...hat.com>, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm-ppc@...r.kernel.org,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        kvmarm@...ts.cs.columbia.edu, Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to
 kvm_get_dirty_log()

On Tue, Dec 17, 2019 at 12:40:38PM -0800, Sean Christopherson wrote:
> +int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
> +		      int *is_dirty, struct kvm_memory_slot **memslot)
>  {
>  	struct kvm_memslots *slots;
> -	struct kvm_memory_slot *memslot;
>  	int i, as_id, id;
>  	unsigned long n;
>  	unsigned long any = 0;
>  
> +	*memslot = NULL;
> +	*is_dirty = 0;
> +
>  	as_id = log->slot >> 16;
>  	id = (u16)log->slot;
>  	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
>  		return -EINVAL;
>  
>  	slots = __kvm_memslots(kvm, as_id);
> -	memslot = id_to_memslot(slots, id);
> -	if (!memslot->dirty_bitmap)
> +	*memslot = id_to_memslot(slots, id);
> +	if (!(*memslot)->dirty_bitmap)
>  		return -ENOENT;
>  
> -	n = kvm_dirty_bitmap_bytes(memslot);
> +	kvm_arch_sync_dirty_log(kvm, *memslot);

Should this line belong to previous patch?

> +
> +	n = kvm_dirty_bitmap_bytes(*memslot);
>  
>  	for (i = 0; !any && i < n/sizeof(long); ++i)
> -		any = memslot->dirty_bitmap[i];
> +		any = (*memslot)->dirty_bitmap[i];
>  
> -	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
> +	if (copy_to_user(log->dirty_bitmap, (*memslot)->dirty_bitmap, n))
>  		return -EFAULT;
>  
>  	if (any)
> -- 
> 2.24.1

-- 
Peter Xu