Re: [PATCH] net: hns: Prefer struct_size over open coded arithmetic

[lipeng (Y)]

 On 2021/10/11 17:01, 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.
>
> So, take the opportunity to refactor the hnae_handle structure to switch
> the last member to flexible array, changing the code accordingly. Also,
> fix the comment in the hnae_vf_cb structure to inform that the ae_handle
> member must be the last member.
>
> Then, use the struct_size() helper to do the arithmetic instead of the
> argument "size + count * size" in the kzalloc() function.
>
> This code was detected with the help of Coccinelle and audited and fixed
> manually.
>
> [1] 
> https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments 
>
>
> Signed-off-by: Len Baker <len.baker@xxxxxxx>
> ---
>   drivers/net/ethernet/hisilicon/hns/hnae.h          | 2 +-
>   drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c  | 5 ++---
>   drivers/net/ethernet/hisilicon/hns/hns_dsaf_main.h | 2 +-
>   3 files changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/net/ethernet/hisilicon/hns/hnae.h 
> b/drivers/net/ethernet/hisilicon/hns/hnae.h
> index 2b7db1c22321..d46e8f999019 100644
> --- a/drivers/net/ethernet/hisilicon/hns/hnae.h
> +++ b/drivers/net/ethernet/hisilicon/hns/hnae.h
> @@ -558,7 +558,7 @@ struct hnae_handle {
>       enum hnae_media_type media_type;
>       struct list_head node;    /* list to hnae_ae_dev->handle_list */
>       struct hnae_buf_ops *bops; /* operation for the buffer */
> -    struct hnae_queue **qs;  /* array base of all queues */
> +    struct hnae_queue *qs[];  /* flexible array of all queues */
>   };
>
>   #define ring_to_dev(ring) ((ring)->q->dev->dev)
> diff --git a/drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c 
> b/drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c
> index 75e4ec569da8..e81116ad9bdf 100644
> --- a/drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c
> +++ b/drivers/net/ethernet/hisilicon/hns/hns_ae_adapt.c
> @@ -81,8 +81,8 @@ static struct hnae_handle *hns_ae_get_handle(struct 
> hnae_ae_dev *dev,
>       vfnum_per_port = hns_ae_get_vf_num_per_port(dsaf_dev, port_id);
>       qnum_per_vf = hns_ae_get_q_num_per_vf(dsaf_dev, port_id);
>
> -    vf_cb = kzalloc(sizeof(*vf_cb) +
> -            qnum_per_vf * sizeof(struct hnae_queue *), GFP_KERNEL);
> +    vf_cb = kzalloc(struct_size(vf_cb, ae_handle.qs, qnum_per_vf),
> +            GFP_KERNEL);
>       if (unlikely(!vf_cb)) {
>           dev_err(dsaf_dev->dev, "malloc vf_cb fail!\n");
>           ae_handle = ERR_PTR(-ENOMEM);
> @@ -108,7 +108,6 @@ static struct hnae_handle 
> *hns_ae_get_handle(struct hnae_ae_dev *dev,
>           goto vf_id_err;
>       }
>
> -    ae_handle->qs = (struct hnae_queue **)(&ae_handle->qs + 1);


 This line can not delete. ae_handle->qs is for PF.



>       for (i = 0; i < qnum_per_vf; i++) {



 This loop actually start from &ae_handle->qs + 1, which is the queue
 offset for VF.


>           ae_handle->qs[i] = &ring_pair_cb->q;
>           ae_handle->qs[i]->rx_ring.q = ae_handle->qs[i];
> diff --git a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_main.h 
> b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_main.h
> index cba04bfa0b3f..5526a10caac5 100644
> --- a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_main.h
> +++ b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_main.h
> @@ -210,7 +210,7 @@ struct hnae_vf_cb {
>       u8 port_index;
>       struct hns_mac_cb *mac_cb;
>       struct dsaf_device *dsaf_dev;
> -    struct hnae_handle  ae_handle; /* must be the last number */
> +    struct hnae_handle  ae_handle; /* must be the last member */
>   };
>
>   struct dsaf_int_xge_src {
> --
> 2.25.1
>
>
> .
>
>
> .