linux-kernel - Re: [PATCH v2 1/7] dmaengine: idxd: fix memory leak in error handling path of idxd_setup

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Message-ID: <f44a4303-d106-408c-ba59-911fe7b9a290@nvidia.com>
Date: Tue, 18 Feb 2025 08:32:14 -0800
From: Fenghua Yu <fenghuay@...dia.com>
To: Shuai Xue <xueshuai@...ux.alibaba.com>, vinicius.gomes@...el.com,
 dave.jiang@...el.com, vkoul@...nel.org
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/7] dmaengine: idxd: fix memory leak in error handling
 path of idxd_setup_wqs

Hi, Shuai,

On 2/14/25 21:44, Shuai Xue wrote:
> Memory allocated for wqs is not freed if an error occurs during
> idxd_setup_wqs(). To fix it, free the allocated memory in the reverse
> order of allocation before exiting the function in case of an error.
>
> Fixes: a8563a33a5e2 ("dmanegine: idxd: reformat opcap output to match bitmap_parse() input")
> Signed-off-by: Shuai Xue <xueshuai@...ux.alibaba.com>
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
>   drivers/dma/idxd/init.c | 20 +++++++++++++++++---
>   1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index b946f78f85e1..b85736fd25bd 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -169,8 +169,8 @@ static int idxd_setup_wqs(struct idxd_device *idxd)
>   
>   	idxd->wq_enable_map = bitmap_zalloc_node(idxd->max_wqs, GFP_KERNEL, dev_to_node(dev));
>   	if (!idxd->wq_enable_map) {
> -		kfree(idxd->wqs);
> -		return -ENOMEM;
> +		rc = -ENOMEM;
> +		goto err_bitmap;
>   	}
>   
>   	for (i = 0; i < idxd->max_wqs; i++) {
> @@ -191,6 +191,7 @@ static int idxd_setup_wqs(struct idxd_device *idxd)
>   		rc = dev_set_name(conf_dev, "wq%d.%d", idxd->id, wq->id);
>   		if (rc < 0) {
>   			put_device(conf_dev);
> +			kfree(wq);
>   			goto err;
>   		}
>   
> @@ -204,6 +205,7 @@ static int idxd_setup_wqs(struct idxd_device *idxd)
>   		wq->wqcfg = kzalloc_node(idxd->wqcfg_size, GFP_KERNEL, dev_to_node(dev));
>   		if (!wq->wqcfg) {
>   			put_device(conf_dev);
> +			kfree(wq);
>   			rc = -ENOMEM;
>   			goto err;
>   		}
> @@ -211,7 +213,9 @@ static int idxd_setup_wqs(struct idxd_device *idxd)
>   		if (idxd->hw.wq_cap.op_config) {
>   			wq->opcap_bmap = bitmap_zalloc(IDXD_MAX_OPCAP_BITS, GFP_KERNEL);
>   			if (!wq->opcap_bmap) {
> +				kfree(wq->wqcfg);
>   				put_device(conf_dev);
> +				kfree(wq);
>   				rc = -ENOMEM;
>   				goto err;
>   			}
> @@ -225,11 +229,21 @@ static int idxd_setup_wqs(struct idxd_device *idxd)
>   	return 0;
>   
>    err:
> -	while (--i >= 0) {
> +	while (i-- > 0) {

Why changed to "i-- > 0" here? Before coming to here, the mem areas 
allocated for wqs[i] are freed already and there is not need to free 
them again here, right? And if i>1, mem areas for wqs[0] won't be freed 
and will leak, right?

>   		wq = idxd->wqs[i];
> +		if (idxd->hw.wq_cap.op_config)
> +			bitmap_free(wq->opcap_bmap);
> +		kfree(wq->wqcfg);
>   		conf_dev = wq_confdev(wq);
>   		put_device(conf_dev);
> +		kfree(wq);
> +
>   	}
> +	bitmap_free(idxd->wq_enable_map);
> +
> +err_bitmap:
> +	kfree(idxd->wqs);
> +
>   	return rc;
>   }
>   

Thanks.


-Fenghua