firmware: arm_ffa: Fix memory leak by freeing notifier callback node

JIRA: https://issues.redhat.com/browse/RHEL-102691

commit a833d31
Author: Sudeep Holla <sudeep.holla@arm.com>
Date: Wed, 28 May 2025 09:49:41 +0100

    Commit e057344 ("firmware: arm_ffa: Add interfaces to request
    notification callbacks") adds support for notifier callbacks by allocating
    and inserting a callback node into a hashtable during registration of
    notifiers. However, during unregistration, the code only removes the
    node from the hashtable without freeing the associated memory, resulting
    in a memory leak.

    Resolve the memory leak issue by ensuring the allocated notifier callback
    node is properly freed after it is removed from the hashtable entry.

    Fixes: e057344 ("firmware: arm_ffa: Add interfaces to request notification callbacks")
    Message-Id: <20250528-ffa_notif_fix-v1-1-5ed7bc7f8437@arm.com>
    Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
    Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

Signed-off-by: Marcin Juszkiewicz <mjuszkiewicz@redhat.com>

Author: hrw

drivers/firmware/arm_ffa/driver.c

@@ -1284,6 +1284,7 @@ update_notifier_cb(struct ffa_device *dev, int notify_id, void *cb,
 		hash_add(drv_info->notifier_hash, &cb_info->hnode, notify_id);
 	} else {
 		hash_del(&cb_info->hnode);
+		kfree(cb_info);
 	}
 
 	return 0;