From: Namjae Jeon linkinjeon@kernel.org
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@vger.kernel.org Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-20477 Signed-off-by: Namjae Jeon linkinjeon@kernel.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ksmbd/server.c | 1 + 1 file changed, 1 insertion(+)
--- a/fs/ksmbd/server.c +++ b/fs/ksmbd/server.c @@ -614,6 +614,7 @@ err_unregister: static void __exit ksmbd_server_exit(void) { ksmbd_server_shutdown(); + rcu_barrier(); ksmbd_release_inode_hash(); }