From: Namjae Jeon <linkinjeon@xxxxxxxxxx>
commit eb307d09fe15844fdaebeb8cc8c9b9e925430aa5 upstream.
racy issue is triggered the bug by racing between closing a connection
and rmmod. In ksmbd, rcu_barrier() is not called at module unload time,
so nothing prevents ksmbd from getting unloaded while it still has RCU
callbacks pending. It leads to trigger unintended execution of kernel
code locally and use to defeat protections such as Kernel Lockdown
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: zdi-disclosures@xxxxxxxxxxxxxx # ZDI-CAN-20477
Signed-off-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ksmbd/server.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/ksmbd/server.c
+++ b/fs/ksmbd/server.c
@@ -611,6 +611,7 @@ err_unregister:
static void __exit ksmbd_server_exit(void)
{
ksmbd_server_shutdown();
+ rcu_barrier();
ksmbd_release_inode_hash();
}
