linux-kernel - Re: [PATCH 1/4] drm/msm: fix memleak on release

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Message-ID: <20191030100146.GC4691@localhost>
Date:   Wed, 30 Oct 2019 11:01:46 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     David Airlie <airlied@...ux.ie>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-media@...r.kernel.org, linux-s390@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Johan Hovold <johan@...nel.org>,
        stable <stable@...r.kernel.org>,
        Jordan Crouse <jcrouse@...eaurora.org>,
        Harald Freudenberger <freude@...ux.ibm.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Fabien Dessenne <fabien.dessenne@...com>
Subject: Re: [PATCH 1/4] drm/msm: fix memleak on release

On Thu, Oct 10, 2019 at 03:13:30PM +0200, Johan Hovold wrote:
> If a process is interrupted while accessing the "gpu" debugfs file and
> the drm device struct_mutex is contended, release() could return early
> and fail to free related resources.
> 
> Note that the return value from release() is ignored.
> 
> Fixes: 4f776f4511c7 ("drm/msm/gpu: Convert the GPU show function to use the GPU state")
> Cc: stable <stable@...r.kernel.org>     # 4.18
> Cc: Jordan Crouse <jcrouse@...eaurora.org>
> Cc: Rob Clark <robdclark@...il.com>
> Signed-off-by: Johan Hovold <johan@...nel.org>
> ---

Rob, Sean,

Sending a reminder about this one, which is not yet in linux-next.

Perhaps Daniel can pick it up otherwise?

Thanks,
Johan

>  drivers/gpu/drm/msm/msm_debugfs.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_debugfs.c b/drivers/gpu/drm/msm/msm_debugfs.c
> index 6be879578140..1c74381a4fc9 100644
> --- a/drivers/gpu/drm/msm/msm_debugfs.c
> +++ b/drivers/gpu/drm/msm/msm_debugfs.c
> @@ -47,12 +47,8 @@ static int msm_gpu_release(struct inode *inode, struct file *file)
>  	struct msm_gpu_show_priv *show_priv = m->private;
>  	struct msm_drm_private *priv = show_priv->dev->dev_private;
>  	struct msm_gpu *gpu = priv->gpu;
> -	int ret;
> -
> -	ret = mutex_lock_interruptible(&show_priv->dev->struct_mutex);
> -	if (ret)
> -		return ret;
>  
> +	mutex_lock(&show_priv->dev->struct_mutex);
>  	gpu->funcs->gpu_state_put(show_priv->state);
>  	mutex_unlock(&show_priv->dev->struct_mutex);