RE: [PATCH v6 12/12] rpmsg: Fix kfree() of static memory on setting driver_override

[Biju Das <biju.das.jz@xxxxxxxxxxxxxx>]

Hi Krzysztof Kozlowski,

Thanks for the patch.

> Subject: [PATCH v6 12/12] rpmsg: Fix kfree() of static memory on setting
> driver_override
> 
> The driver_override field from platform driver should not be initialized
> from static memory (string literal) because the core later kfree() it, for
> example when driver_override is set via sysfs.
> 
> Use dedicated helper to set driver_override properly.
> 
> Fixes: 950a7388f02b ("rpmsg: Turn name service into a stand alone driver")
> Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface")
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> ---
>  drivers/rpmsg/rpmsg_internal.h | 13 +++++++++++--
>  drivers/rpmsg/rpmsg_ns.c       | 14 ++++++++++++--
>  include/linux/rpmsg.h          |  6 ++++--
>  3 files changed, 27 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/rpmsg/rpmsg_internal.h
> b/drivers/rpmsg/rpmsg_internal.h index d4b23fd019a8..1a2fb8edf5d3 100644
> --- a/drivers/rpmsg/rpmsg_internal.h
> +++ b/drivers/rpmsg/rpmsg_internal.h
> @@ -94,10 +94,19 @@ int rpmsg_release_channel(struct rpmsg_device *rpdev,
>   */
>  static inline int rpmsg_ctrldev_register_device(struct rpmsg_device
> *rpdev)  {
> +	int ret;
> +
>  	strcpy(rpdev->id.name, "rpmsg_ctrl");
> -	rpdev->driver_override = "rpmsg_ctrl";
> +	ret = driver_set_override(&rpdev->dev, &rpdev->driver_override,
> +				  "rpmsg_ctrl", strlen("rpmsg_ctrl"));

Is it not possible to use rpdev->id.name instead of "rpmsg_ctrl" ?
rpdev->id.name has "rpmsg_ctrl" from strcpy(rpdev->id.name, "rpmsg_ctrl");

Same for "rpmsg_ns" as well

Cheers,
Biju


> +	if (ret)
> +		return ret;
> +
> +	ret = rpmsg_register_device(rpdev);
> +	if (ret)
> +		kfree(rpdev->driver_override);
> 
> -	return rpmsg_register_device(rpdev);
> +	return ret;
>  }
> 
>  #endif
> diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c index
> 762ff1ae279f..95a51543f5ad 100644
> --- a/drivers/rpmsg/rpmsg_ns.c
> +++ b/drivers/rpmsg/rpmsg_ns.c
> @@ -20,12 +20,22 @@
>   */
>  int rpmsg_ns_register_device(struct rpmsg_device *rpdev)  {
> +	int ret;
> +
>  	strcpy(rpdev->id.name, "rpmsg_ns");
> -	rpdev->driver_override = "rpmsg_ns";
> +	ret = driver_set_override(&rpdev->dev, &rpdev->driver_override,
> +				  "rpmsg_ns", strlen("rpmsg_ns"));
> +	if (ret)
> +		return ret;
> +
>  	rpdev->src = RPMSG_NS_ADDR;
>  	rpdev->dst = RPMSG_NS_ADDR;
> 
> -	return rpmsg_register_device(rpdev);
> +	ret = rpmsg_register_device(rpdev);
> +	if (ret)
> +		kfree(rpdev->driver_override);
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL(rpmsg_ns_register_device);
> 
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h index
> 02fa9116cd60..20c8cd1cde21 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -41,7 +41,9 @@ struct rpmsg_channel_info {
>   * rpmsg_device - device that belong to the rpmsg bus
>   * @dev: the device struct
>   * @id: device id (used to match between rpmsg drivers and devices)
> - * @driver_override: driver name to force a match
> + * @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.
>   * @src: local address
>   * @dst: destination address
>   * @ept: the rpmsg endpoint of this channel @@ -51,7 +53,7 @@ struct
> rpmsg_channel_info {  struct rpmsg_device {
>  	struct device dev;
>  	struct rpmsg_device_id id;
> -	char *driver_override;
> +	const char *driver_override;
>  	u32 src;
>  	u32 dst;
>  	struct rpmsg_endpoint *ept;
> --
> 2.32.0
> 
> 
> _______________________________________________