[PATCH v6 07/16] firmware: arm_scmi: Reject out of range DT protocol IDs

[Sudeep Holla <sudeep.holla@kernel.org>]

SCMI protocol IDs carried in message headers are limited by
MSG_PROTOCOL_ID_MASK. The DT parsing paths noticed protocol IDs
outside that range, but only logged an error and then kept processing
the invalid value.

That lets a malformed 32-bit DT reg value reach helpers which take a u8
protocol ID, where it can be truncated and/or treated as a different
protocol.

For channel setup, two different out-of-range values can also be used as
distinct IDR keys while aliasing the generated SCMI protocol identity.

Skip DT protocol nodes whose reg value does not fit the SCMI protocol ID
field before setting up channels or creating protocol devices.

Fixes: 05a2801d8b90 ("firmware: arm_scmi: Use dedicated devices to initialize channels")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>
---
 drivers/firmware/arm_scmi/driver.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index d17559c897a9..0735c6374269 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -2873,9 +2873,11 @@ static int scmi_channels_setup(struct scmi_info *info)
 		if (of_property_read_u32(child, "reg", &prot_id))
 			continue;
 
-		if (!FIELD_FIT(MSG_PROTOCOL_ID_MASK, prot_id))
+		if (!FIELD_FIT(MSG_PROTOCOL_ID_MASK, prot_id)) {
 			dev_err(info->dev,
 				"Out of range protocol %d\n", prot_id);
+			continue;
+		}
 
 		ret = scmi_txrx_setup(info, child, prot_id);
 		if (ret)
@@ -3339,8 +3341,10 @@ static int scmi_probe(struct platform_device *pdev)
 		if (of_property_read_u32(child, "reg", &prot_id))
 			continue;
 
-		if (!FIELD_FIT(MSG_PROTOCOL_ID_MASK, prot_id))
+		if (!FIELD_FIT(MSG_PROTOCOL_ID_MASK, prot_id)) {
 			dev_err(dev, "Out of range protocol %d\n", prot_id);
+			continue;
+		}
 
 		if (!scmi_is_protocol_implemented(handle, prot_id)) {
 			dev_err(dev, "SCMI protocol %d not implemented\n",

-- 
2.43.0