[PATCH] firmware: arm_scmi: avoid double free in error flow

[Wen Yang]

If device_register() fails, both put_device() and kfree()
are called, ending with a double free of the scmi_dev.

Calling kfree() is needed only when a failure happens between the
allocation of the scmi_dev and its registration, so move it to
there and remove it from the error flow.

Fixes: 46edb8d1322c ("firmware: arm_scmi: provide the mandatory device release callback")
Signed-off-by: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx>
Cc: Sudeep Holla <sudeep.holla@xxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 drivers/firmware/arm_scmi/bus.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 92f843ea..7a30952 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -135,8 +135,10 @@ struct scmi_device *
 		return NULL;
 
 	id = ida_simple_get(&scmi_bus_id, 1, 0, GFP_KERNEL);
-	if (id < 0)
-		goto free_mem;
+	if (id < 0) {
+		kfree(scmi_dev);
+		return NULL;
+	}
 
 	scmi_dev->id = id;
 	scmi_dev->protocol_id = protocol;
@@ -154,8 +156,6 @@ struct scmi_device *
 put_dev:
 	put_device(&scmi_dev->dev);
 	ida_simple_remove(&scmi_bus_id, id);
-free_mem:
-	kfree(scmi_dev);
 	return NULL;
 }
 
-- 
1.8.3.1