linux-kernel - Re: [PATCH v2] MIPS: KVM: Return directly after a failed copy_from_user() in kvm_arch_vcpu

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Date:   Thu, 19 Jan 2017 11:27:52 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     SF Markus Elfring <elfring@...rs.sourceforge.net>,
        kvm@...r.kernel.org, linux-mips@...ux-mips.org,
        James Hogan <james.hogan@...tec.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Ralf Bächle <ralf@...ux-mips.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v2] MIPS: KVM: Return directly after a failed
 copy_from_user() in kvm_arch_vcpu_ioctl()



On 19/01/2017 11:20, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Thu, 19 Jan 2017 11:10:26 +0100
> 
> * Return directly after a call of the function "copy_from_user" failed
>   in a case block.
> 
> * Delete the jump label "out" which became unnecessary with
>   this refactoring.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
> 
> V2:
> A label was also removed at the end.
> 
>  arch/mips/kvm/mips.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index 06a60b19acfb..3534a0b9efed 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -1152,10 +1152,8 @@ long kvm_arch_vcpu_ioctl(struct file *filp, unsigned int ioctl,
>  		{
>  			struct kvm_mips_interrupt irq;
>  
> -			r = -EFAULT;
>  			if (copy_from_user(&irq, argp, sizeof(irq)))
> -				goto out;
> -
> +				return -EFAULT;
>  			kvm_debug("[%d] %s: irq: %d\n", vcpu->vcpu_id, __func__,
>  				  irq.irq);
>  
> @@ -1165,17 +1163,14 @@ long kvm_arch_vcpu_ioctl(struct file *filp, unsigned int ioctl,
>  	case KVM_ENABLE_CAP: {
>  		struct kvm_enable_cap cap;
>  
> -		r = -EFAULT;
>  		if (copy_from_user(&cap, argp, sizeof(cap)))
> -			goto out;
> +			return -EFAULT;
>  		r = kvm_vcpu_ioctl_enable_cap(vcpu, &cap);
>  		break;
>  	}
>  	default:
>  		r = -ENOIOCTLCMD;
>  	}
> -
> -out:
>  	return r;
>  }
>  
> 

Removing the label makes the patch worthwhile.

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>