Re: [PATCH][next] vfio/iommu_type1: Use struct_size() for kzalloc()

From: Alex Williamson <alex.williamson@redhat.com>
To: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Cornelia Huck <cohuck@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-hardening@vger.kernel.org
Subject: Re: [PATCH][next] vfio/iommu_type1: Use struct_size() for kzalloc()
Date: Mon, 24 May 2021 13:48:01 -0600	[thread overview]
Message-ID: <20210524134801.406bc4bf@x1.home.shazbot.org> (raw)
In-Reply-To: <20210513230155.GA217517@embeddedor>

On Thu, 13 May 2021 18:01:55 -0500
"Gustavo A. R. Silva" <gustavoars@kernel.org> wrote:

> Make use of the struct_size() helper instead of an open-coded version,
> in order to avoid any potential type mistakes or integer overflows
> that, in the worst scenario, could lead to heap overflows.
> 
> This code was detected with the help of Coccinelle and, audited and
> fixed manually.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index a0747c35a778..a3e925a41b0d 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -2795,7 +2795,7 @@ static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
>  		return 0;
>  	}
>  
> -	size = sizeof(*cap_iovas) + (iovas * sizeof(*cap_iovas->iova_ranges));
> +	size = struct_size(cap_iovas, iova_ranges, iovas);
>  
>  	cap_iovas = kzalloc(size, GFP_KERNEL);
>  	if (!cap_iovas)

Looks good, applied to vfio for-linus branch for v5.13.  Thanks,

Alex