ksmbd: fix null pointer dereference in alloc_preauth_hash()

commit c8b5b7c5da7d0c31c9b7190b4a7bba5281fc4780 upstream.

The Client send malformed smb2 negotiate request. ksmbd return error
response. Subsequently, the client can send smb2 session setup even
thought conn->preauth_info is not allocated.
This patch add KSMBD_SESS_NEED_SETUP status of connection to ignore
session setup request if smb2 negotiate phase is not complete.

Cc: stable@vger.kernel.org
Tested-by: Steve French <stfrench@microsoft.com>
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-26505
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Jan Alexander Preissler <akendo@akendo.eu>
Signed-off-by: Sujana Subramaniam <sujana.subramaniam@sap.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 24 insertions, 5 deletions

diff --git a/fs/smb/server/connection.h b/fs/smb/server/connection.h
index 29ba91fc5407..45421269ddd8 100644
--- a/fs/smb/server/connection.h
+++ b/fs/smb/server/connection.h
@@ -27,6 +27,7 @@ enum {
 	KSMBD_SESS_EXITING,
 	KSMBD_SESS_NEED_RECONNECT,
 	KSMBD_SESS_NEED_NEGOTIATE,
+	KSMBD_SESS_NEED_SETUP,
 	KSMBD_SESS_RELEASING
 };
 
@@ -195,6 +196,11 @@ static inline bool ksmbd_conn_need_negotiate(struct ksmbd_conn *conn)
 	return READ_ONCE(conn->status) == KSMBD_SESS_NEED_NEGOTIATE;
 }
 
+static inline bool ksmbd_conn_need_setup(struct ksmbd_conn *conn)
+{
+	return READ_ONCE(conn->status) == KSMBD_SESS_NEED_SETUP;
+}
+
 static inline bool ksmbd_conn_need_reconnect(struct ksmbd_conn *conn)
 {
 	return READ_ONCE(conn->status) == KSMBD_SESS_NEED_RECONNECT;
@@ -225,6 +231,11 @@ static inline void ksmbd_conn_set_need_negotiate(struct ksmbd_conn *conn)
 	WRITE_ONCE(conn->status, KSMBD_SESS_NEED_NEGOTIATE);
 }
 
+static inline void ksmbd_conn_set_need_setup(struct ksmbd_conn *conn)
+{
+	WRITE_ONCE(conn->status, KSMBD_SESS_NEED_SETUP);
+}
+
 static inline void ksmbd_conn_set_need_reconnect(struct ksmbd_conn *conn)
 {
 	WRITE_ONCE(conn->status, KSMBD_SESS_NEED_RECONNECT);
diff --git a/fs/smb/server/mgmt/user_session.c b/fs/smb/server/mgmt/user_session.c
index 82dcc86a32c5..408f47220c07 100644
--- a/fs/smb/server/mgmt/user_session.c
+++ b/fs/smb/server/mgmt/user_session.c
@@ -373,12 +373,12 @@ void destroy_previous_session(struct ksmbd_conn *conn,
 	ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_RECONNECT);
 	err = ksmbd_conn_wait_idle_sess_id(conn, id);
 	if (err) {
-		ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_NEGOTIATE);
+		ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_SETUP);
 		goto out;
 	}
 	ksmbd_destroy_file_table(&prev_sess->file_table);
 	prev_sess->state = SMB2_SESSION_EXPIRED;
-	ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_NEGOTIATE);
+	ksmbd_all_conn_set_status(id, KSMBD_SESS_NEED_SETUP);
 out:
 	up_write(&conn->session_lock);
 	up_write(&sessions_table_lock);
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 85e7bc3a2bd3..ae47450dc40f 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -1252,7 +1252,7 @@ int smb2_handle_negotiate(struct ksmbd_work *work)
 	}
 
 	conn->srv_sec_mode = le16_to_cpu(rsp->SecurityMode);
-	ksmbd_conn_set_need_negotiate(conn);
+	ksmbd_conn_set_need_setup(conn);
 
 err_out:
 	if (rc)
@@ -1273,6 +1273,9 @@ static int alloc_preauth_hash(struct ksmbd_session *sess,
 	if (sess->Preauth_HashValue)
 		return 0;
 
+	if (!conn->preauth_info)
+		return -ENOMEM;
+
 	sess->Preauth_HashValue = kmemdup(conn->preauth_info->Preauth_HashValue,
 					  PREAUTH_HASHVALUE_SIZE, GFP_KERNEL);
 	if (!sess->Preauth_HashValue)
@@ -1688,6 +1691,11 @@ int smb2_sess_setup(struct ksmbd_work *work)
 
 	ksmbd_debug(SMB, "Received request for session setup\n");
 
+	if (!ksmbd_conn_need_setup(conn) && !ksmbd_conn_good(conn)) {
+		work->send_no_response = 1;
+		return rc;
+	}
+
 	WORK_BUFFERS(work, req, rsp);
 
 	rsp->StructureSize = cpu_to_le16(9);
@@ -1919,7 +1927,7 @@ out_err:
 			if (try_delay) {
 				ksmbd_conn_set_need_reconnect(conn);
 				ssleep(5);
-				ksmbd_conn_set_need_negotiate(conn);
+				ksmbd_conn_set_need_setup(conn);
 			}
 		}
 		smb2_set_err_rsp(work);
@@ -2249,7 +2257,7 @@ int smb2_session_logoff(struct ksmbd_work *work)
 		ksmbd_free_user(sess->user);
 		sess->user = NULL;
 	}
-	ksmbd_all_conn_set_status(sess_id, KSMBD_SESS_NEED_NEGOTIATE);
+	ksmbd_all_conn_set_status(sess_id, KSMBD_SESS_NEED_SETUP);
 
 	rsp->StructureSize = cpu_to_le16(4);
 	err = ksmbd_iov_pin_rsp(work, rsp, sizeof(struct smb2_logoff_rsp));