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

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Message-ID: <20170119120838.GF31545@jhogan-linux.le.imgtec.org>
Date:   Thu, 19 Jan 2017 12:08:38 +0000
From:   James Hogan <james.hogan@...tec.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
CC:     SF Markus Elfring <elfring@...rs.sourceforge.net>,
        <kvm@...r.kernel.org>, <linux-mips@...ux-mips.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Ralf Bächle <ralf@...ux-mips.org>,
        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 Thu, Jan 19, 2017 at 11:27:52AM +0100, Paolo Bonzini wrote:
> 
> 
> 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>

Thanks Markus & Paolo. Looks better now. I'll apply for 4.11.

Cheers
James

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