ksmbd: fix out of bounds in init_smb2_rsp_hdr()

If client send smb2 negotiate request and then send smb1 negotiate
request, init_smb2_rsp_hdr is called for smb1 negotiate request since
need_neg is set to false. This patch ignore smb1 packets after ->need_neg
is set to false.

Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-21541
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/server.c

@@ -286,6 +286,7 @@ static void handle_ksmbd_work(struct work_struct *wk)
 static int queue_ksmbd_work(struct ksmbd_conn *conn)
 {
 	struct ksmbd_work *work;
+	int err;
 
 	work = ksmbd_alloc_work_struct();
 	if (!work) {
@@ -297,7 +298,11 @@ static int queue_ksmbd_work(struct ksmbd_conn *conn)
 	work->request_buf = conn->request_buf;
 	conn->request_buf = NULL;
 
-	ksmbd_init_smb_server(work);
+	err = ksmbd_init_smb_server(work);
+	if (err) {
+		ksmbd_free_work_struct(work);
+		return 0;
+	}
 
 	ksmbd_conn_enqueue_request(work);
 	atomic_inc(&conn->r_count);

fs/smb/server/smb_common.c

@@ -388,26 +388,29 @@ static struct smb_version_cmds smb1_server_cmds[1] = {
 	[SMB_COM_NEGOTIATE_EX]	= { .proc = smb1_negotiate, },
 };
 
-static void init_smb1_server(struct ksmbd_conn *conn)
+static int init_smb1_server(struct ksmbd_conn *conn)
 {
 	conn->ops = &smb1_server_ops;
 	conn->cmds = smb1_server_cmds;
 	conn->max_cmds = ARRAY_SIZE(smb1_server_cmds);
+	return 0;
 }
 
-void ksmbd_init_smb_server(struct ksmbd_work *work)
+int ksmbd_init_smb_server(struct ksmbd_work *work)
 {
 	struct ksmbd_conn *conn = work->conn;
 	__le32 proto;
 
-	if (conn->need_neg == false)
-		return;
-
 	proto = *(__le32 *)((struct smb_hdr *)work->request_buf)->Protocol;
+	if (conn->need_neg == false) {
 		if (proto == SMB1_PROTO_NUMBER)
-		init_smb1_server(conn);
-	else
-		init_smb3_11_server(conn);
+			return -EINVAL;
+		return 0;
+	}
+
+	if (proto == SMB1_PROTO_NUMBER)
+		return init_smb1_server(conn);
+	return init_smb3_11_server(conn);
 }
 
 int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work, int info_level,

fs/smb/server/smb_common.h

@@ -427,7 +427,7 @@ bool ksmbd_smb_request(struct ksmbd_conn *conn);
 
 int ksmbd_lookup_dialect_by_id(__le16 *cli_dialects, __le16 dialects_count);
 
-void ksmbd_init_smb_server(struct ksmbd_work *work);
+int ksmbd_init_smb_server(struct ksmbd_work *work);
 
 struct ksmbd_kstat;
 int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work,