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

From: Rishabh Bhatnagar
Date: Tue Aug 03 2021 - 18:22:40 EST

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.

Change-Id: I1214ec2c4c92c4a3ca5fa73de11e0e403b13b46a
Signed-off-by: Rishabh Bhatnagar <rishabhb@xxxxxxxxxxxxxx>
drivers/firmware/arm_scmi/driver.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 9b2e8d4..518c7b9 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1430,7 +1430,7 @@ 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 +1443,7 @@ 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;

@@ -1482,6 +1482,13 @@ static int scmi_probe(struct platform_device *pdev)

return 0;
+ scmi_notification_exit(&info->handle);
+ idr_for_each(&info->tx_idr, info->desc->ops->chan_free, &info->tx_idr);
+ idr_for_each(&info->rx_idr, info->desc->ops->chan_free, &info->rx_idr);
+ return ret;

void scmi_free_channel(struct scmi_chan_info *cinfo, struct idr *idr, int id)
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