Re: [PATCH v1 2/2] dmaengine: idxd: fix potential NULL pointer dereference on wq setup error path

[Dave Jiang <dave.jiang@intel.com>]

On 5/21/25 11:33 PM, Shuai Xue wrote:
> 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@vger.kernel.org
> Reported-by: Colin King <colin.i.king@gmail.com>
> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  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 760b7d81fcd8..bf57ad30d613 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)