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: [email protected] # ZDI-CAN-21541 Signed-off-by: Namjae Jeon <[email protected]>
namjaejeon · Jul 23, 2023 · d149845 · d149845
1 parent 03bef3d
commit d149845
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Showing 3 changed files with 18 additions and 10 deletions.
diff --git a/server.c b/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);

diff --git a/smb_common.c b/smb_common.c
@@ -425,27 +425,30 @@ 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;
 }
 #endif
 
-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)
+			return -EINVAL;
+		return 0;
+	}
+
 	if (proto == SMB1_PROTO_NUMBER)
-		init_smb1_server(conn);
-	else
-		init_smb3_11_server(conn);
+		return init_smb1_server(conn);
+	return init_smb3_11_server(conn);
 }
 
 int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work, int info_level,

diff --git a/smb_common.h b/smb_common.h
@@ -470,7 +470,7 @@ 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);
 
 bool ksmbd_pdu_size_has_room(unsigned int pdu);