From 6b445c0dc53f1c5778258bd673c0b61f6dd93a69 Mon Sep 17 00:00:00 2001
From: Vlad Khorsun <hvlad@users.sourceforge.net>
Date: Fri, 20 Sep 2024 17:30:32 +0300
Subject: [PATCH] Catch possible stack overflow when preparing and compiling
 user statements

---
 src/dsql/dsql.cpp | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/dsql/dsql.cpp b/src/dsql/dsql.cpp
index 18ad503847..a69b672fc3 100644
--- a/src/dsql/dsql.cpp
+++ b/src/dsql/dsql.cpp
@@ -43,6 +43,7 @@
 #include "../common/intlobj_new.h"
 #include "../jrd/jrd.h"
 #include "../jrd/status.h"
+#include "../jrd/ibsetjmp.h"
 #include "../common/CharSet.h"
 #include "../dsql/Parser.h"
 #include "../dsql/ddl_proto.h"
@@ -85,6 +86,7 @@ using namespace Firebird;
 static ULONG	get_request_info(thread_db*, DsqlRequest*, ULONG, UCHAR*);
 static dsql_dbb*	init(Jrd::thread_db*, Jrd::Attachment*);
 static DsqlRequest* prepareRequest(thread_db*, dsql_dbb*, jrd_tra*, ULONG, const TEXT*, USHORT, unsigned, bool);
+static DsqlRequest* safePrepareRequest(thread_db*, dsql_dbb*, jrd_tra*, ULONG, const TEXT*, USHORT, bool);
 static RefPtr<DsqlStatement> prepareStatement(thread_db*, dsql_dbb*, jrd_tra*, ULONG, const TEXT*, USHORT,
 	unsigned, bool, ntrace_result_t* traceResult);
 static UCHAR*	put_item(UCHAR, const USHORT, const UCHAR*, UCHAR*, const UCHAR* const);
@@ -260,7 +262,7 @@ DsqlRequest* DSQL_prepare(thread_db* tdbb,
 	{
 		// Allocate a new request block and then prepare the request.
 
-		dsqlRequest = prepareRequest(tdbb, database, transaction, length, string, dialect,
+		dsqlRequest = safePrepareRequest(tdbb, database, transaction, length, string, dialect,
 			prepareFlags, isInternalRequest);
 
 		// Can not prepare a CREATE DATABASE/SCHEMA statement
@@ -335,7 +337,7 @@ void DSQL_execute_immediate(thread_db* tdbb, Jrd::Attachment* attachment, jrd_tr
 
 	try
 	{
-		dsqlRequest = prepareRequest(tdbb, database, *tra_handle, length, string, dialect,
+		dsqlRequest = safePrepareRequest(tdbb, database, *tra_handle, length, string, dialect,
 			0, isInternalRequest);
 
 		const auto dsqlStatement = dsqlRequest->getDsqlStatement();
@@ -439,6 +441,23 @@ static dsql_dbb* init(thread_db* tdbb, Jrd::Attachment* attachment)
 	return attachment->att_dsql_instance;
 }
 
+// Use SEH frame when preparing user requests to catch possible stack overflows
+static DsqlRequest* safePrepareRequest(thread_db* tdbb, dsql_dbb* database, jrd_tra* transaction,
+	ULONG textLength, const TEXT* text, USHORT clientDialect, bool isInternalRequest)
+{
+	if (isInternalRequest)
+		return prepareRequest(tdbb, database, transaction, textLength, text, clientDialect, true);
+
+#ifdef WIN_NT
+	START_CHECK_FOR_EXCEPTIONS(NULL);
+#endif
+	return prepareRequest(tdbb, database, transaction, textLength, text, clientDialect, false);
+
+#ifdef WIN_NT
+	END_CHECK_FOR_EXCEPTIONS(NULL);
+#endif
+}
+
 
 // Prepare a request for execution.
 // Note: caller is responsible for pool handling.