firmware: arm_scmi: Free mailbox channels if probe fails

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.

    | arm-scmi soc:qcom,scmi: timed out in resp(caller: version_get+0x84/0x140)
    | arm-scmi soc:qcom,scmi: unable to communicate with SCMI
    | 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.

     | rx_callback+0x24/0x160
     | mbox_chan_received_data+0x44/0x94
     | __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.

Link: https://lore.kernel.org/r/1628111999-21595-1-git-send-email-rishabhb@codeaurora.org
Tested-by: Cristian Marussi <cristian.marussi@arm.com>
Reviewed-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 00fcacd..b28111e 100644 (file)
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1787,6 +1787,21 @@ void scmi_protocol_device_unrequest(const struct scmi_device_id *id_table)
        mutex_unlock(&scmi_requested_devices_mtx);
 }
 
+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;
@@ -1833,7 +1848,7 @@ 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");
@@ -1846,7 +1861,7 @@ 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);
@@ -1885,6 +1900,12 @@ 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)
@@ -1896,7 +1917,6 @@ 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);
@@ -1920,14 +1940,7 @@ 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);
 }
 
 static ssize_t protocol_version_show(struct device *dev,