linux-kernel - Re: [PATCH] KVM: vgic: Fix potential double free dist->spis in __kvm_vgic

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Message-ID: <115fbbb3-73d5-444a-0aec-61bca0dea435@redhat.com>
Date:   Thu, 28 Nov 2019 09:49:02 +0100
From:   Auger Eric <eric.auger@...hat.com>
To:     linmiaohe <linmiaohe@...wei.com>, maz@...nel.org,
        pbonzini@...hat.com, rkrcmar@...hat.com, james.morse@....com,
        julien.thierry.kdev@...il.com, suzuki.poulose@....com,
        christoffer.dall@....com, catalin.marinas@....com,
        gregkh@...uxfoundation.org, will@...nel.org,
        andre.przywara@....com, tglx@...utronix.de
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH] KVM: vgic: Fix potential double free dist->spis in
 __kvm_vgic_destroy()

Hi,

On 11/28/19 7:38 AM, linmiaohe wrote:
> From: Miaohe Lin <linmiaohe@...wei.com>
> 
> In kvm_vgic_dist_init() called from kvm_vgic_map_resources(), if
> dist->vgic_model is invalid, dist->spis will be freed without set
> dist->spis = NULL. And in vgicv2 resources clean up path,
> __kvm_vgic_destroy() will be called to free allocated resources.
> And dist->spis will be freed again in clean up chain because we
> forget to set dist->spis = NULL in kvm_vgic_dist_init() failed
> path. So double free would happen.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Reviewed-by: Eric Auger <eric.auger@...hat.com>

Thanks

Eric

> ---
>  virt/kvm/arm/vgic/vgic-init.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
> index 53e3969dfb52..c17c29beeb72 100644
> --- a/virt/kvm/arm/vgic/vgic-init.c
> +++ b/virt/kvm/arm/vgic/vgic-init.c
> @@ -171,6 +171,7 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis)
>  			break;
>  		default:
>  			kfree(dist->spis);
> +			dist->spis = NULL;
>  			return -EINVAL;
>  		}
>  	}
>