On 30-03-24, 16:23, 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]
> Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
> Signed-off-by: Erick Archer <erick.archer@xxxxxxxxxxx>
> ---
> Changes in v2:
> - Add the "Reviewed-by:" tag.
> - Rebase against linux-next.
>
> Previous versions:
> v1 -> https://lore.kernel.org/linux-hardening/20240128115236.4791-1-erick.archer@xxxxxxx/
>
> Hi everyone,
>
> This patch seems to be lost. Gustavo reviewed it on January 30, 2024
> but the patch has not been applied since.
>
> Thanks,
> Erick
> ---
> 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 fbf048f432bf..73a5cfb4da8a 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);
How is one better than the other?
> if (!pl08x->phy_chans) {
> ret = -ENOMEM;
> goto out_no_phychans;
> --
> 2.25.1
--
~Vinod
