2021-09-04 13:25:49

by Len Baker

Subject: [PATCH] clk: ti: composite: Prefer kcalloc over open coded arithmetic

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

So, use the purpose specific kcalloc() function instead of the argument
size * count in the kzalloc() function.

[1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments

Signed-off-by: Len Baker <[email protected]>
---
drivers/clk/ti/composite.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/ti/composite.c b/drivers/clk/ti/composite.c
index eaa43575cfa5..eb5ce9735c7d 100644
--- a/drivers/clk/ti/composite.c
+++ b/drivers/clk/ti/composite.c
@@ -253,7 +253,7 @@ int __init ti_clk_add_component(struct device_node *node, struct clk_hw *hw,
return -EINVAL;
}

- parent_names = kzalloc((sizeof(char *) * num_parents), GFP_KERNEL);
+ parent_names = kcalloc(num_parents, sizeof(char *), GFP_KERNEL);
if (!parent_names)
return -ENOMEM;

--
2.25.1

2022-05-21 16:38:35

by Stephen Boyd

Subject: Re: [PATCH] clk: ti: composite: Prefer kcalloc over open coded arithmetic

Quoting Len Baker (2021-09-04 06:17:14)
> As noted in the "Deprecated Interfaces, Language Features, Attributes,
> and Conventions" documentation [1], size calculations (especially
> multiplication) should not be performed in memory allocator (or similar)
> function arguments due to the risk of them overflowing. This could lead
> to values wrapping around and a smaller allocation being made than the
> caller was expecting. Using those allocations could lead to linear
> overflows of heap memory and other misbehaviors.
>
> So, use the purpose specific kcalloc() function instead of the argument
> size * count in the kzalloc() function.
>
> [1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
>
> Signed-off-by: Len Baker <[email protected]>
> ---

Applied to clk-next