linux-kernel - Re: [PATCH net-next v2] ice: Adjust over allocation of memory in ice_sched_add_root_node() and ice_sched_add

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Message-ID: <c71e8bc5-8702-47d1-9d01-84f8c57b32a2@intel.com>
Date: Mon, 8 Jul 2024 12:12:32 +0200
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Aleksandr Mishin <amishin@...rgos.ru>
CC: Jesse Brandeburg <jesse.brandeburg@...el.com>, Tony Nguyen
	<anthony.l.nguyen@...el.com>, "David S. Miller" <davem@...emloft.net>, "Eric
 Dumazet" <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, <intel-wired-lan@...ts.osuosl.org>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<lvc-project@...uxtesting.org>, Simon Horman <horms@...nel.org>
Subject: Re: [PATCH net-next v2] ice: Adjust over allocation of memory in
 ice_sched_add_root_node() and ice_sched_add_node()

On 7/6/24 16:05, Aleksandr Mishin wrote:
> In ice_sched_add_root_node() and ice_sched_add_node() there are calls to
> devm_kcalloc() in order to allocate memory for array of pointers to
> 'ice_sched_node' structure. But in this calls there are 'sizeof(*root)'
> instead of 'sizeof(root)' and 'sizeof(*node)' instead of 'sizeof(node)'.
> So memory is allocated for structures instead pointers. This lead to
> significant over allocation of memory.
> 
> Adjust over allocation of memory by correcting devm_kcalloc() parameters.

Last three sentences are not correct.
Better commit message would be also more concise.

> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Suggested-by: Simon Horman <horms@...nel.org>
> Signed-off-by: Aleksandr Mishin <amishin@...rgos.ru>
> ---
> v2:
>    - Update comment, remove 'Fixes' tag and change the tree from 'net' to
>      'net-next' as suggested by Simon
> 	(https://lore.kernel.org/all/20240706095258.GB1481495@kernel.org/)
> v1: https://lore.kernel.org/all/20240705163620.12429-1-amishin@t-argos.ru/
> 
>   drivers/net/ethernet/intel/ice/ice_sched.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_sched.c b/drivers/net/ethernet/intel/ice/ice_sched.c
> index ecf8f5d60292..d8b6054f3436 100644
> --- a/drivers/net/ethernet/intel/ice/ice_sched.c
> +++ b/drivers/net/ethernet/intel/ice/ice_sched.c
> @@ -28,9 +28,8 @@ ice_sched_add_root_node(struct ice_port_info *pi,
>   	if (!root)
>   		return -ENOMEM;
>   
> -	/* coverity[suspicious_sizeof] */

good to clear that, thanks

>   	root->children = devm_kcalloc(ice_hw_to_dev(hw), hw->max_children[0],
> -				      sizeof(*root), GFP_KERNEL);
> +				      sizeof(root), GFP_KERNEL);

Your change makes code to use the correct type as sizeof() argument,
however, I would like to also make it the correct entity, so:
sizeof(*root->children) // == sizeof(root->children[0])

For the reference
  562│ struct ice_sched_node {
...
  565│         struct ice_sched_node **children;


>   	if (!root->children) {
>   		devm_kfree(ice_hw_to_dev(hw), root);
>   		return -ENOMEM;
> @@ -186,10 +185,9 @@ ice_sched_add_node(struct ice_port_info *pi, u8 layer,
>   	if (!node)
>   		return -ENOMEM;
>   	if (hw->max_children[layer]) {
> -		/* coverity[suspicious_sizeof] */
>   		node->children = devm_kcalloc(ice_hw_to_dev(hw),
>   					      hw->max_children[layer],
> -					      sizeof(*node), GFP_KERNEL);
> +					      sizeof(node), GFP_KERNEL);

ditto

>   		if (!node->children) {
>   			devm_kfree(ice_hw_to_dev(hw), node);
>   			return -ENOMEM;