[PATCH 1/2] firmware: arm_scmi: Roll back partial protocol table registration

scmi_protocol_table_register() can leave earlier requests registered when
a later entry in the same ID table fails. Each request retains a pointer
to the driver's ID table, so a failed module load can leave a dangling
pointer after the module storage is released.

Unrequest only the successfully registered prefix, in reverse order,
before returning the failure. Leave the failed entry and the remaining
entries untouched because matching requests can be owned by another
driver.

Fixes: 2858f6e5f064 ("firmware: arm_scmi: Add multiple protocols registration support")
Reported-by: Sashiko <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>
---
 drivers/firmware/arm_scmi/bus.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

Hi,

Couple of more issues[2] reported as part of review of [1]. These
are addressing those issues.

Regards,
Sudeep

[1] https://patch.msgid.link/[email protected]
[2] https://sashiko.dev/#/patchset/[email protected]

diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index df396ab638dd..af3d28717cd2 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -135,17 +135,6 @@ static int scmi_protocol_device_request(const struct scmi_device_id *id_table)
 	return ret;
 }
 
-static int scmi_protocol_table_register(const struct scmi_device_id *id_table)
-{
-	int ret = 0;
-	const struct scmi_device_id *entry;
-
-	for (entry = id_table; entry->name && ret == 0; entry++)
-		ret = scmi_protocol_device_request(entry);
-
-	return ret;
-}
-
 /**
  * scmi_protocol_device_unrequest  - Helper to unrequest a device
  *
@@ -191,6 +180,26 @@ static void scmi_protocol_device_unrequest(const struct scmi_device_id *id_table
 	}
 }
 
+static int scmi_protocol_table_register(const struct scmi_device_id *id_table)
+{
+	const struct scmi_device_id *entry;
+	int ret;
+
+	for (entry = id_table; entry->name; entry++) {
+		ret = scmi_protocol_device_request(entry);
+		if (ret)
+			goto err_unrequest;
+	}
+
+	return 0;
+
+err_unrequest:
+	while (entry != id_table)
+		scmi_protocol_device_unrequest(--entry);
+
+	return ret;
+}
+
 static void
 scmi_protocol_table_unregister(const struct scmi_device_id *id_table)
 {
-- 
2.43.0