Re: [kvm:queue 6/21] arch/x86/kvm/cpuid.c:564:39: sparse: dereference of noderef expression

[Paolo Bonzini <pbonzini@redhat.com>]

Il 06/11/2013 15:46, Borislav Petkov ha scritto:
> From: Borislav Petkov <bp@suse.de>
> Subject: [PATCH] kvm, cpuid: Fix sparse warning
> 
> We need to copy padding to kernel space first before looking at it.
> 
> Reported-by: kbuild test robot <fengguang.wu@intel.com>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> ---
>  arch/x86/kvm/cpuid.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 8f66fba804e4..c6976257eff5 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -564,6 +564,7 @@ static bool sanity_check_entries(struct kvm_cpuid_entry2 __user *entries,
>  				 __u32 num_entries, unsigned int ioctl_type)
>  {
>  	int i;
> +	__u32 pad[3];
>  
>  	if (ioctl_type != KVM_GET_EMULATED_CPUID)
>  		return false;
> @@ -577,9 +578,10 @@ static bool sanity_check_entries(struct kvm_cpuid_entry2 __user *entries,
>  	 * sheds a tear.
>  	 */
>  	for (i = 0; i < num_entries; i++) {
> -		if (entries[i].padding[0] ||
> -		    entries[i].padding[1] ||
> -		    entries[i].padding[2])
> +		if (copy_from_user(pad, entries[i].padding, sizeof(pad)))
> +			return true;
> +
> +		if (pad[0] || pad[1] || pad[2])
>  			return true;
>  	}
>  	return false;
> 

Applied by Gleb -- thanks.

Paolo