four fixes, also for stable

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Merge tag 'v6.12-rc6-ksmbd-fixes' of git://git.samba.org/ksmbd

Pull smb server fixes from Steve French:
 "Four fixes, all also marked for stable:

   - fix two potential use after free issues

   - fix OOM issue with many simultaneous requests

   - fix missing error check in RPC pipe handling"

* tag 'v6.12-rc6-ksmbd-fixes' of git://git.samba.org/ksmbd:
  ksmbd: check outstanding simultaneous SMB operations
  ksmbd: fix slab-use-after-free in smb3_preauth_hash_rsp
  ksmbd: fix slab-use-after-free in ksmbd_smb2_session_create
  ksmbd: Fix the missing xa_store error check

fs/smb/server/connection.c

@@ -70,6 +70,7 @@ struct ksmbd_conn *ksmbd_conn_alloc(void)
 	atomic_set(&conn->req_running, 0);
 	atomic_set(&conn->r_count, 0);
 	atomic_set(&conn->refcnt, 1);
+	atomic_set(&conn->mux_smb_requests, 0);
 	conn->total_credits = 1;
 	conn->outstanding_credits = 0;
 

fs/smb/server/connection.h

@@ -107,6 +107,7 @@ struct ksmbd_conn {
 	__le16				signing_algorithm;
 	bool				binding;
 	atomic_t			refcnt;
+	atomic_t			mux_smb_requests;
 };
 
 struct ksmbd_conn_ops {

fs/smb/server/mgmt/user_session.c

@@ -90,7 +90,7 @@ static int __rpc_method(char *rpc_name)
 
 int ksmbd_session_rpc_open(struct ksmbd_session *sess, char *rpc_name)
 {
-	struct ksmbd_session_rpc *entry;
+	struct ksmbd_session_rpc *entry, *old;
 	struct ksmbd_rpc_command *resp;
 	int method;
 
@@ -106,16 +106,19 @@ int ksmbd_session_rpc_open(struct ksmbd_session *sess, char *rpc_name)
 	entry->id = ksmbd_ipc_id_alloc();
 	if (entry->id < 0)
 		goto free_entry;
-	xa_store(&sess->rpc_handle_list, entry->id, entry, GFP_KERNEL);
+	old = xa_store(&sess->rpc_handle_list, entry->id, entry, GFP_KERNEL);
+	if (xa_is_err(old))
+		goto free_id;
 
 	resp = ksmbd_rpc_open(sess, entry->id);
 	if (!resp)
-		goto free_id;
+		goto erase_xa;
 
 	kvfree(resp);
 	return entry->id;
-free_id:
+erase_xa:
 	xa_erase(&sess->rpc_handle_list, entry->id);
+free_id:
 	ksmbd_rpc_id_free(entry->id);
 free_entry:
 	kfree(entry);
@@ -175,6 +178,7 @@ static void ksmbd_expire_session(struct ksmbd_conn *conn)
 	unsigned long id;
 	struct ksmbd_session *sess;
 
+	down_write(&sessions_table_lock);
 	down_write(&conn->session_lock);
 	xa_for_each(&conn->sessions, id, sess) {
 		if (atomic_read(&sess->refcnt) == 0 &&
@@ -188,6 +192,7 @@ static void ksmbd_expire_session(struct ksmbd_conn *conn)
 		}
 	}
 	up_write(&conn->session_lock);
+	up_write(&sessions_table_lock);
 }
 
 int ksmbd_session_register(struct ksmbd_conn *conn,
@@ -229,7 +234,6 @@ void ksmbd_sessions_deregister(struct ksmbd_conn *conn)
 			}
 		}
 	}
-	up_write(&sessions_table_lock);
 
 	down_write(&conn->session_lock);
 	xa_for_each(&conn->sessions, id, sess) {
@@ -249,6 +253,7 @@ void ksmbd_sessions_deregister(struct ksmbd_conn *conn)
 		}
 	}
 	up_write(&conn->session_lock);
+	up_write(&sessions_table_lock);
 }
 
 struct ksmbd_session *ksmbd_session_lookup(struct ksmbd_conn *conn,

fs/smb/server/server.c

@@ -238,11 +238,11 @@ static void __handle_ksmbd_work(struct ksmbd_work *work,
 	} while (is_chained == true);
 
 send:
-	if (work->sess)
-		ksmbd_user_session_put(work->sess);
 	if (work->tcon)
 		ksmbd_tree_connect_put(work->tcon);
 	smb3_preauth_hash_rsp(work);
+	if (work->sess)
+		ksmbd_user_session_put(work->sess);
 	if (work->sess && work->sess->enc && work->encrypted &&
 	    conn->ops->encrypt_resp) {
 		rc = conn->ops->encrypt_resp(work);
@@ -270,6 +270,7 @@ static void handle_ksmbd_work(struct work_struct *wk)
 
 	ksmbd_conn_try_dequeue_request(work);
 	ksmbd_free_work_struct(work);
+	atomic_dec(&conn->mux_smb_requests);
 	/*
 	 * Checking waitqueue to dropping pending requests on
 	 * disconnection. waitqueue_active is safe because it
@@ -291,6 +292,15 @@ static int queue_ksmbd_work(struct ksmbd_conn *conn)
 	struct ksmbd_work *work;
 	int err;
 
+	err = ksmbd_init_smb_server(conn);
+	if (err)
+		return 0;
+
+	if (atomic_inc_return(&conn->mux_smb_requests) >= conn->vals->max_credits) {
+		atomic_dec_return(&conn->mux_smb_requests);
+		return -ENOSPC;
+	}
+
 	work = ksmbd_alloc_work_struct();
 	if (!work) {
 		pr_err("allocation for work failed\n");
@@ -301,12 +311,6 @@ static int queue_ksmbd_work(struct ksmbd_conn *conn)
 	work->request_buf = conn->request_buf;
 	conn->request_buf = NULL;
 
-	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);
 	/* update activity on connection */

fs/smb/server/smb_common.c

@@ -388,6 +388,10 @@ static struct smb_version_ops smb1_server_ops = {
 	.set_rsp_status = set_smb1_rsp_status,
 };
 
+static struct smb_version_values smb1_server_values = {
+	.max_credits = SMB2_MAX_CREDITS,
+};
+
 static int smb1_negotiate(struct ksmbd_work *work)
 {
 	return ksmbd_smb_negotiate_common(work, SMB_COM_NEGOTIATE);
@@ -399,18 +403,18 @@ static struct smb_version_cmds smb1_server_cmds[1] = {
 
 static int init_smb1_server(struct ksmbd_conn *conn)
 {
+	conn->vals = &smb1_server_values;
 	conn->ops = &smb1_server_ops;
 	conn->cmds = smb1_server_cmds;
 	conn->max_cmds = ARRAY_SIZE(smb1_server_cmds);
 	return 0;
 }
 
-int ksmbd_init_smb_server(struct ksmbd_work *work)
+int ksmbd_init_smb_server(struct ksmbd_conn *conn)
 {
-	struct ksmbd_conn *conn = work->conn;
 	__le32 proto;
 
-	proto = *(__le32 *)((struct smb_hdr *)work->request_buf)->Protocol;
+	proto = *(__le32 *)((struct smb_hdr *)conn->request_buf)->Protocol;
 	if (conn->need_neg == false) {
 		if (proto == SMB1_PROTO_NUMBER)
 			return -EINVAL;

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);
 
-int ksmbd_init_smb_server(struct ksmbd_work *work);
+int ksmbd_init_smb_server(struct ksmbd_conn *conn);
 
 struct ksmbd_kstat;
 int ksmbd_populate_dot_dotdot_entries(struct ksmbd_work *work,