linux-kernel - Re: [PATCH v2] RDMA/erdma: Use vcalloc() instead of vzalloc()

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Message-ID: <4dbdf24b-f725-e194-f1ec-f1510759a24c@linux.alibaba.com>
Date: Thu, 21 Aug 2025 17:26:10 +0800
From: Cheng Xu <chengyou@...ux.alibaba.com>
To: Qianfeng Rong <rongqianfeng@...o.com>,
 Kai Shen <kaishen@...ux.alibaba.com>, Jason Gunthorpe <jgg@...pe.ca>,
 Leon Romanovsky <leon@...nel.org>, linux-rdma@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: Markus.Elfring@....de
Subject: Re: [PATCH v2] RDMA/erdma: Use vcalloc() instead of vzalloc()



On 8/21/25 3:22 PM, Qianfeng Rong wrote:
> Replace vzalloc() with vcalloc() in vmalloc_to_dma_addrs().  As noted
> in the kernel documentation [1], open-coded multiplication in allocator
> arguments is discouraged because it can lead to integer overflow.
> 
> Use vcalloc() to gain built-in overflow protection, making memory
> allocation safer when calculating allocation size compared to explicit
> multiplication.
> 
> [1]: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> 
> Signed-off-by: Qianfeng Rong <rongqianfeng@...o.com>
> ---
> v2: change sizeof(dma_addr_t) to sizeof(*pg_dma) to improve code
>     robustness as suggested by Markus.
> ---
>  drivers/infiniband/hw/erdma/erdma_verbs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Thanks.

Reviewed-by: Cheng Xu <chengyou@...ux.alibaba.com>

> diff --git a/drivers/infiniband/hw/erdma/erdma_verbs.c b/drivers/infiniband/hw/erdma/erdma_verbs.c
> index 996860f49b2f..109a3f3de911 100644
> --- a/drivers/infiniband/hw/erdma/erdma_verbs.c
> +++ b/drivers/infiniband/hw/erdma/erdma_verbs.c
> @@ -671,7 +671,7 @@ static u32 vmalloc_to_dma_addrs(struct erdma_dev *dev, dma_addr_t **dma_addrs,
>  
>  	npages = (PAGE_ALIGN((u64)buf + len) - PAGE_ALIGN_DOWN((u64)buf)) >>
>  		 PAGE_SHIFT;
> -	pg_dma = vzalloc(npages * sizeof(dma_addr_t));
> +	pg_dma = vcalloc(npages, sizeof(*pg_dma));
>  	if (!pg_dma)
>  		return 0;
>