linux-hardening - Re: [PATCH] dmaengine: pl08x: Use kcalloc() instead of kzalloc()

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Date: Tue, 30 Jan 2024 12:33:30 -0600
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Erick Archer <erick.archer@....com>, Vinod Koul <vkoul@...nel.org>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH] dmaengine: pl08x: Use kcalloc() instead of kzalloc()



On 1/28/24 05:52, Erick Archer wrote:
> This is an effort to get rid of all multiplications from allocation
> functions in order to prevent integer overflows [1].
> 
> Here the multiplication is obviously safe because the "channels"
> member can only be 8 or 2. This value is set when the "vendor_data"
> structs are initialized.
> 
> static struct vendor_data vendor_pl080 = {
> 	[...]
> 	.channels = 8,
> 	[...]
> };
> 
> static struct vendor_data vendor_nomadik = {
> 	[...]
> 	.channels = 8,
> 	[...]
> };
> 
> static struct vendor_data vendor_pl080s = {
> 	[...]
> 	.channels = 8,
> 	[...]
> };
> 
> static struct vendor_data vendor_pl081 = {
> 	[...]
> 	.channels = 2,
> 	[...]
> };
> 
> However, using kcalloc() is more appropriate [1] and improves
> readability. This patch has no effect on runtime behavior.
> 
> Link: https://github.com/KSPP/linux/issues/162 [1]
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Signed-off-by: Erick Archer <erick.archer@....com>

Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>

Thanks!
-- 
Gustavo

> ---
>   drivers/dma/amba-pl08x.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
> index eea8bd33b4b7..e40766108787 100644
> --- a/drivers/dma/amba-pl08x.c
> +++ b/drivers/dma/amba-pl08x.c
> @@ -2855,8 +2855,8 @@ static int pl08x_probe(struct amba_device *adev, const struct amba_id *id)
>   	}
> 
>   	/* Initialize physical channels */
> -	pl08x->phy_chans = kzalloc((vd->channels * sizeof(*pl08x->phy_chans)),
> -			GFP_KERNEL);
> +	pl08x->phy_chans = kcalloc(vd->channels, sizeof(*pl08x->phy_chans),
> +				   GFP_KERNEL);
>   	if (!pl08x->phy_chans) {
>   		ret = -ENOMEM;
>   		goto out_no_phychans;
> --
> 2.25.1
>