linux-kernel - Re: [PATCH v2] dmaengine: idxd: fix potential NULL pointer dereference on wq setup error path

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Message-ID: <1064beba-4904-47f9-983f-8f7c56c6d7e3@linux.alibaba.com>
Date: Tue, 29 Jul 2025 14:01:07 +0800
From: Shuai Xue <xueshuai@...ux.alibaba.com>
To: vinicius.gomes@...el.com, dave.jiang@...el.com, fenghuay@...dia.com,
 vkoul@...nel.org
Cc: dmaengine@...r.kernel.org, colin.i.king@...il.com,
 linux-kernel@...r.kernel.org, dan.carpenter@...aro.org
Subject: Re: [PATCH v2] dmaengine: idxd: fix potential NULL pointer
 dereference on wq setup error path



在 2025/6/7 11:45, Shuai Xue 写道:
> If wq allocation fails during the initial iteration of the loop,
> `conf_dev` is still NULL.  However, the existing error handling via
> `goto err` would attempt to call `put_device(conf_dev)`, leading to a
> NULL pointer dereference.
> 
> This issue occurs because there's no dedicated error label for the WQ
> allocation failure case, causing it to fall through to an incorrect
> error path.
> 
> Fix this by introducing a new error label `err_wq`, ensuring that we
> only invoke `put_device(conf_dev)` when `conf_dev` is valid.
> 
> Fixes: 3fd2f4bc010c ("dmaengine: idxd: fix memory leak in error handling path of idxd_setup_wqs")
> Cc: stable@...r.kernel.org
> Reported-by: Colin King <colin.i.king@...il.com>
> Closes: https://lore.kernel.org/dmaengine/aDQt3_rZjX-VuHJW@stanley.mountain
> Signed-off-by: Shuai Xue <xueshuai@...ux.alibaba.com>
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
> changes since v1:
> - add Reviewed-by tag from Dave Jiang
> - add Reported-by tag from Dan Carpenter and its Closes link
> ---
>   drivers/dma/idxd/init.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 80355d03004d..a818d4799770 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -196,7 +196,7 @@ static int idxd_setup_wqs(struct idxd_device *idxd)
>   		wq = kzalloc_node(sizeof(*wq), GFP_KERNEL, dev_to_node(dev));
>   		if (!wq) {
>   			rc = -ENOMEM;
> -			goto err;
> +			goto err_wq;
>   		}
>   
>   		idxd_dev_set_type(&wq->idxd_dev, IDXD_DEV_WQ);
> @@ -246,6 +246,7 @@ static int idxd_setup_wqs(struct idxd_device *idxd)
>   	put_device(conf_dev);
>   	kfree(wq);
>   
> +err_wq:
>   	while (--i >= 0) {
>   		wq = idxd->wqs[i];
>   		if (idxd->hw.wq_cap.op_config)

Hi, Vinod,

Gentle Ping.

Thanks.
Shuai