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Subject: Re: [patch] kvm: svm: fix potential get_num_contig_pages overflow
To:     David Rientjes <rientjes@google.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Joerg Roedel <joro@8bytes.org>
Cc:     Cfir Cohen <cfir@google.com>,
        Brijesh Singh <brijesh.singh@amd.com>,
        Tom Lendacky <thomas.lendacky@amd.com>, x86@kernel.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <alpine.DEB.2.21.1903191517380.256304@chino.kir.corp.google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
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Message-ID: <7a0590c0-330c-3144-94f2-3edcc7a92739@redhat.com>
Date:   Fri, 5 Apr 2019 20:49:33 +0200
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On 19/03/19 23:19, David Rientjes wrote:
> get_num_contig_pages() could potentially overflow int so make its type 
> consistent with its usage.
> 
> Reported-by: Cfir Cohen <cfir@google.com>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  arch/x86/kvm/svm.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -6422,11 +6422,11 @@ static int sev_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  	return ret;
>  }
>  
> -static int get_num_contig_pages(int idx, struct page **inpages,
> -				unsigned long npages)
> +static unsigned long get_num_contig_pages(unsigned long idx,
> +				struct page **inpages, unsigned long npages)
>  {
>  	unsigned long paddr, next_paddr;
> -	int i = idx + 1, pages = 1;
> +	unsigned long i = idx + 1, pages = 1;
>  
>  	/* find the number of contiguous pages starting from idx */
>  	paddr = __sme_page_pa(inpages[idx]);
> @@ -6445,12 +6445,12 @@ static int get_num_contig_pages(int idx, struct page **inpages,
>  
>  static int sev_launch_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  {
> -	unsigned long vaddr, vaddr_end, next_vaddr, npages, size;
> +	unsigned long vaddr, vaddr_end, next_vaddr, npages, pages, size, i;
>  	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
>  	struct kvm_sev_launch_update_data params;
>  	struct sev_data_launch_update_data *data;
>  	struct page **inpages;
> -	int i, ret, pages;
> +	int ret;
>  
>  	if (!sev_guest(kvm))
>  		return -ENOTTY;
> 

I had missed it, and now I've queued it.

Paolo