2024-01-28 11:53:07

by Erick Archer

Subject: [PATCH] dmaengine: pl08x: Use kcalloc() instead of kzalloc()

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 <[email protected]>
---
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

2024-01-30 18:33:54

by Gustavo A. R. Silva

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 <[email protected]>

Reviewed-by: Gustavo A. R. Silva <[email protected]>

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
>