[PATCH net v2] net: mctp i3c: clean up notifier and buses if driver register fails

[Myeonghun Pak]

mctp_i3c_mod_init() registers the I3C bus notifier and then walks the
existing buses with i3c_for_each_bus_locked(mctp_i3c_bus_add_new, NULL)
before registering the I3C device driver.  If i3c_driver_register()
fails, the function returns the error directly, leaving the notifier
registered and every mctp_i3c_bus object created for the existing buses
allocated.  The notifier is left pointing into the module that failed to
load and the bus list is leaked.

Mirror the module exit path on this failure: unregister the notifier and
tear down the buses that were added before returning the error.

This issue was identified during our ongoing static-analysis research while
reviewing kernel code.

Fixes: c8755b29b58e ("mctp i3c: MCTP I3C driver")
Co-developed-by: Ijae Kim <ae878000@xxxxxxxxx>
Signed-off-by: Ijae Kim <ae878000@xxxxxxxxx>
Signed-off-by: Myeonghun Pak <mhun512@xxxxxxxxx>
---
Changes in v2:
- Remove the unmatched i3c_driver_unregister() from the notifier
  registration failure path, as suggested by Jeremy.
- Add Simon Horman to Cc.

 drivers/net/mctp/mctp-i3c.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/mctp/mctp-i3c.c b/drivers/net/mctp/mctp-i3c.c
index 6d2bbae747..88d9e36cd4 100644
--- a/drivers/net/mctp/mctp-i3c.c
+++ b/drivers/net/mctp/mctp-i3c.c
@@ -731,18 +731,21 @@ static __init int mctp_i3c_mod_init(void)
 	int rc;
 
 	rc = i3c_register_notifier(&mctp_i3c_notifier);
-	if (rc < 0) {
-		i3c_driver_unregister(&mctp_i3c_driver);
+	if (rc < 0)
 		return rc;
-	}
 
 	i3c_for_each_bus_locked(mctp_i3c_bus_add_new, NULL);
 
 	rc = i3c_driver_register(&mctp_i3c_driver);
 	if (rc < 0)
-		return rc;
+		goto err_unregister_notifier;

 	return 0;
+
+err_unregister_notifier:
+	i3c_unregister_notifier(&mctp_i3c_notifier);
+	mctp_i3c_bus_remove_all();
+	return rc;
 }

 static __exit void mctp_i3c_mod_exit(void)
--
2.53.0