linux-kernel - Re: [PATCH][next][V2] iommu/mediatek: Fix unsigned domid comparison with less than zero

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Date:   Thu, 4 Feb 2021 15:45:23 +0000
From:   Will Deacon <will@...nel.org>
To:     Colin King <colin.king@...onical.com>
Cc:     Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next][V2] iommu/mediatek: Fix unsigned domid comparison
 with less than zero

On Thu, Feb 04, 2021 at 03:00:01PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> Currently the check for domid < 0 is always false because domid
> is unsigned. Fix this by casting domid to an int before making
> the comparison.
> 
> Addresses-Coverity: ("Unsigned comparison against 0")
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
> 
> V2: cast domid rather than making it an int. Replace L with : in
>     the commit message.
> 
> ---
>  drivers/iommu/mtk_iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 0ad14a7604b1..1f262621ef19 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -645,7 +645,7 @@ static void mtk_iommu_get_resv_regions(struct device *dev,
>  	struct iommu_resv_region *region;
>  	int prot = IOMMU_WRITE | IOMMU_READ;
>  
> -	if (domid < 0)
> +	if ((int)domid < 0)
>  		return;
>  	curdom = data->plat_data->iova_region + domid;
>  	for (i = 0; i < data->plat_data->iova_region_nr; i++) {

Thanks, Colin.

Acked-by: Will Deacon <will@...nel.org>

Will