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* [PATCH] ice: Prefer kcalloc over open coded arithmetic
@ 2021-09-05  6:50 Len Baker
  2021-09-12 20:41 ` [Intel-wired-lan] " Gustavo A. R. Silva
  0 siblings, 1 reply; 2+ messages in thread
From: Len Baker @ 2021-09-05  6:50 UTC (permalink / raw)
  To: Jesse Brandeburg, Tony Nguyen, David S. Miller, Jakub Kicinski
  Cc: Len Baker, Kees Cook, intel-wired-lan, netdev, linux-hardening,
	linux-kernel

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.

In this case this is not actually dynamic sizes: both sides of the
multiplication are constant values. However it is best to refactor this
anyway, just to keep the open-coded math idiom out of code.

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 <len.baker@gmx.com>
---
 drivers/net/ethernet/intel/ice/ice_arfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_arfs.c b/drivers/net/ethernet/intel/ice/ice_arfs.c
index 88d98c9e5f91..3071b8e79499 100644
--- a/drivers/net/ethernet/intel/ice/ice_arfs.c
+++ b/drivers/net/ethernet/intel/ice/ice_arfs.c
@@ -513,7 +513,7 @@ void ice_init_arfs(struct ice_vsi *vsi)
 	if (!vsi || vsi->type != ICE_VSI_PF)
 		return;

-	arfs_fltr_list = kzalloc(sizeof(*arfs_fltr_list) * ICE_MAX_ARFS_LIST,
+	arfs_fltr_list = kcalloc(ICE_MAX_ARFS_LIST, sizeof(*arfs_fltr_list),
 				 GFP_KERNEL);
 	if (!arfs_fltr_list)
 		return;
--
2.25.1


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [Intel-wired-lan] [PATCH] ice: Prefer kcalloc over open coded arithmetic
  2021-09-05  6:50 [PATCH] ice: Prefer kcalloc over open coded arithmetic Len Baker
@ 2021-09-12 20:41 ` Gustavo A. R. Silva
  0 siblings, 0 replies; 2+ messages in thread
From: Gustavo A. R. Silva @ 2021-09-12 20:41 UTC (permalink / raw)
  To: Len Baker, Jesse Brandeburg, Tony Nguyen, David S. Miller,
	Jakub Kicinski
  Cc: Kees Cook, netdev, linux-kernel, intel-wired-lan, linux-hardening



On 9/5/21 01:50, Len Baker wrote:
> 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.
> 
> In this case this is not actually dynamic sizes: both sides of the
> multiplication are constant values. However it is best to refactor this
> anyway, just to keep the open-coded math idiom out of code.
> 
> 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 <len.baker@gmx.com>

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

BTW... Len, feel free to CC me on all your patches related to KSPP work. :)

Thanks
--
Gustavo

> ---
>  drivers/net/ethernet/intel/ice/ice_arfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_arfs.c b/drivers/net/ethernet/intel/ice/ice_arfs.c
> index 88d98c9e5f91..3071b8e79499 100644
> --- a/drivers/net/ethernet/intel/ice/ice_arfs.c
> +++ b/drivers/net/ethernet/intel/ice/ice_arfs.c
> @@ -513,7 +513,7 @@ void ice_init_arfs(struct ice_vsi *vsi)
>  	if (!vsi || vsi->type != ICE_VSI_PF)
>  		return;
> 
> -	arfs_fltr_list = kzalloc(sizeof(*arfs_fltr_list) * ICE_MAX_ARFS_LIST,
> +	arfs_fltr_list = kcalloc(ICE_MAX_ARFS_LIST, sizeof(*arfs_fltr_list),
>  				 GFP_KERNEL);
>  	if (!arfs_fltr_list)
>  		return;
> --
> 2.25.1
> 
> _______________________________________________
> Intel-wired-lan mailing list
> Intel-wired-lan@osuosl.org
> https://lists.osuosl.org/mailman/listinfo/intel-wired-lan
> 

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2021-09-12 20:41 ` [Intel-wired-lan] " Gustavo A. R. Silva

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