Re: [PATCH v3] firmware: arm_scmi: Free mailbox channels if probe fails

Cristian Marussi
2021-08-05T10:54:35Z

On Wed, Aug 04, 2021 at 02:19:59PM -0700, Rishabh Bhatnagar wrote:
> Mailbox channels for the base protocol are setup during probe.
> There can be a scenario where probe fails to acquire the base
> protocol due to a timeout leading to cleaning up of all device
> managed memory including the scmi_mailbox structure setup during
> mailbox_chan_setup function.
> [ 12.735104]arm-scmi soc:qcom,scmi: timed out in resp(caller: version_get+0x84/0x140)
> [ 12.735224]arm-scmi soc:qcom,scmi: unable to communicate with SCMI
> [ 12.735947]arm-scmi: probe of soc:qcom,scmi failed with error -110
>
> Now when a message arrives at cpu slightly after the timeout, the mailbox
> controller will try to call the rx_callback of the client and might end
> up accessing freed memory.
> [ 12.758363][ C0] Call trace:
> [ 12.758367][ C0] rx_callback+0x24/0x160
> [ 12.758372][ C0] mbox_chan_received_data+0x44/0x94
> [ 12.758386][ C0] __handle_irq_event_percpu+0xd4/0x240
> This patch frees the mailbox channels setup during probe and adds some more
> error handling in case the probe fails.
>
> Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
> ---
> drivers/firmware/arm_scmi/driver.c | 35 ++++++++++++++++++++++++-----------
> 1 file changed, 24 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index 9b2e8d4..ead3bd3 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -1390,6 +1390,21 @@ void scmi_protocol_device_unrequest(const struct scmi_device_id *id_table)
> mutex_unlock(&scmi_requested_devices_mtx);
> }
>

Hi,

> +static int scmi_cleanup_txrx_channels(struct scmi_info *info)
> +{
> + int ret;
> + struct idr *idr = &info->tx_idr;
> +
> + ret = idr_for_each(idr, info->desc->ops->chan_free, idr);
> + idr_destroy(&info->tx_idr);
> +
> + idr = &info->rx_idr;
> + ret = idr_for_each(idr, info->desc->ops->chan_free, idr);
> + idr_destroy(&info->rx_idr);
> +
> + return ret;
> +}
> +
> static int scmi_probe(struct platform_device *pdev)
> {
> int ret;
> @@ -1430,7 +1445,7 @@ static int scmi_probe(struct platform_device *pdev)
>
> ret = scmi_xfer_info_init(info);
> if (ret)
> - return ret;
> + goto clear_txrx_setup;
>
> if (scmi_notification_init(handle))
> dev_err(dev, "SCMI Notifications NOT available.\n");
> @@ -1443,7 +1458,7 @@ static int scmi_probe(struct platform_device *pdev)
> ret = scmi_protocol_acquire(handle, SCMI_PROTOCOL_BASE);
> if (ret) {
> dev_err(dev, "unable to communicate with SCMI\n");
> - return ret;
> + goto notification_exit;
> }
>
> mutex_lock(&scmi_list_mutex);
> @@ -1482,6 +1497,12 @@ static int scmi_probe(struct platform_device *pdev)
> }
>
> return 0;
> +
> +notification_exit:
> + scmi_notification_exit(&info->handle);
> +clear_txrx_setup:
> + scmi_cleanup_txrx_channels(info);
> + return ret;
> }
>
> void scmi_free_channel(struct scmi_chan_info *cinfo, struct idr *idr, int id)
> @@ -1493,7 +1514,6 @@ static int scmi_remove(struct platform_device *pdev)
> {
> int ret = 0, id;
> struct scmi_info *info = platform_get_drvdata(pdev);
> - struct idr *idr = &info->tx_idr;
> struct device_node *child;
>
> mutex_lock(&scmi_list_mutex);
> @@ -1517,14 +1537,7 @@ static int scmi_remove(struct platform_device *pdev)
> idr_destroy(&info->active_protocols);
>
> /* Safe to free channels since no more users */
> - ret = idr_for_each(idr, info->desc->ops->chan_free, idr);
> - idr_destroy(&info->tx_idr);
> -
> - idr = &info->rx_idr;
> - ret = idr_for_each(idr, info->desc->ops->chan_free, idr);
> - idr_destroy(&info->rx_idr);
> -
> - return ret;
> + return scmi_cleanup_txrx_channels(info);
> }
>

Looks good to me.

Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
(Re-tested on for-next/scmi on top of virtio-scmi series)

Thanks,
Cristian