linux-kernel - Re: [PATCH] rpmsg: glink: Release driver

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Message-ID: <dc0e1609-a872-08e7-2801-0ece573181ad@quicinc.com>
Date:   Tue, 17 Jan 2023 17:01:01 -0800
From:   Chris Lew <quic_clew@...cinc.com>
To:     Bjorn Andersson <quic_bjorande@...cinc.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>
CC:     "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>,
        "open list:REMOTE PROCESSOR MESSAGING (RPMSG) SUBSYSTEM" 
        <linux-remoteproc@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] rpmsg: glink: Release driver_override



On 1/9/2023 2:38 PM, Bjorn Andersson wrote:
> Upon termination of the rpmsg_device, driver_override needs to be freed
> to avoid leaking the potentially assigned string.
> 
> Fixes: 42cd402b8fd4 ("rpmsg: Fix kfree() of static memory on setting driver_override")
> Fixes: 39e47767ec9b ("rpmsg: Add driver_override device attribute for rpmsg_device")
> Signed-off-by: Bjorn Andersson <quic_bjorande@...cinc.com>
> ---
>   drivers/rpmsg/qcom_glink_native.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index 8620eea1dc8a..046271e439c5 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -1454,6 +1454,7 @@ static void qcom_glink_rpdev_release(struct device *dev)
>   {
>   	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
>   
> +	kfree(rpdev->driver_override);

I see in Krzysztof's original patch to fix up the driver_override we do 
kfree in other areas of rpmsg.

More of a just curious as to why don't we use the driver_set_override 
function to clear the string? It's mentioned in the rpmsg header that 
the helper should be used.

--- include/linux/rpmsg.h
  * @driver_override: driver name to force a match; do not set directly,
  *                   because core frees it; use driver_set_override() to
  *                   set or clear it.

>   	kfree(rpdev);
>   }
>   
> @@ -1697,6 +1698,7 @@ static void qcom_glink_device_release(struct device *dev)
>   
>   	/* Release qcom_glink_alloc_channel() reference */
>   	kref_put(&channel->refcount, qcom_glink_channel_release);
> +	kfree(rpdev->driver_override);
>   	kfree(rpdev);
>   }
>   
>