linux-kernel - Re: [PATCH RESEND] drm/msm: Add missing check and destroy for alloc_ordered

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Message-ID: <9b53d5f0-e1b1-1ecd-b9b9-efa20b11c916@linaro.org>
Date:   Mon, 9 Jan 2023 00:45:04 +0200
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>, robdclark@...il.com,
        quic_abhinavk@...cinc.com, sean@...rly.run, airlied@...il.com,
        sumit.semwal@...aro.org, christian.koenig@....com
Cc:     linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linaro-mm-sig@...ts.linaro.org, freedreno@...ts.freedesktop.org
Subject: Re: [PATCH RESEND] drm/msm: Add missing check and destroy for
 alloc_ordered_workqueue

On 06/01/2023 10:47, Jiasheng Jiang wrote:
> Add check for the return value of alloc_ordered_workqueue as it may return
> NULL pointer.
> Moreover, use the destroy_workqueue in the later fails in order to avoid
> memory leak.
> 
> Fixes: c8afe684c95c ("drm/msm: basic KMS driver for snapdragon")
> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> ---
>   drivers/gpu/drm/msm/msm_drv.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 8b0b0ac74a6f..b82d938226ad 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -418,6 +418,8 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   	priv->dev = ddev;
>   
>   	priv->wq = alloc_ordered_workqueue("msm", 0);
> +	if (!priv->wq)
> +		return -ENOMEM;
>   
>   	INIT_LIST_HEAD(&priv->objects);
>   	mutex_init(&priv->obj_lock);
> @@ -440,12 +442,12 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   
>   	ret = msm_init_vram(ddev);
>   	if (ret)
> -		return ret;
> +		goto err_destroy_workqueue;
>   
>   	/* Bind all our sub-components: */
>   	ret = component_bind_all(dev, ddev);
>   	if (ret)
> -		return ret;
> +		goto err_destroy_workqueue;
>   
>   	dma_set_max_seg_size(dev, UINT_MAX);
>   
> @@ -540,6 +542,8 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   
>   err_msm_uninit:
>   	msm_drm_uninit(dev);

return ret is missing here. Your code will result in double free.

However the intent was to unroll each and every action of msm_drm_init() 
in msm_drm_uninit(). So in all your cases please goto err_msm_unit.

> +err_destroy_workqueue:
> +	destroy_workqueue(priv->wq);
>   	return ret;
>   }
>   

-- 
With best wishes
Dmitry