From: Namjae Jeon Date: Sat, 22 Mar 2025 00:20:19 +0000 (+0900) Subject: ksmbd: fix use-after-free in ksmbd_sessions_deregister() X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=15a9605f8d69dc85005b1a00c31a050b8625e1aa;p=linux.git ksmbd: fix use-after-free in ksmbd_sessions_deregister() In multichannel mode, UAF issue can occur in session_deregister when the second channel sets up a session through the connection of the first channel. session that is freed through the global session table can be accessed again through ->sessions of connection. Cc: stable@vger.kernel.org Reported-by: Norbert Szetei Tested-by: Norbert Szetei Signed-off-by: Namjae Jeon Signed-off-by: Steve French --- diff --git a/fs/smb/server/mgmt/user_session.c b/fs/smb/server/mgmt/user_session.c index 71c6939dfbf1..1ecca6785ed0 100644 --- a/fs/smb/server/mgmt/user_session.c +++ b/fs/smb/server/mgmt/user_session.c @@ -230,6 +230,9 @@ void ksmbd_sessions_deregister(struct ksmbd_conn *conn) if (!ksmbd_chann_del(conn, sess) && xa_empty(&sess->ksmbd_chann_list)) { hash_del(&sess->hlist); + down_write(&conn->session_lock); + xa_erase(&conn->sessions, sess->id); + up_write(&conn->session_lock); ksmbd_session_destroy(sess); } }