From 83e4de8b64bae0c446e9bea492c754008e053e3c Mon Sep 17 00:00:00 2001
From: Augustin Cavalier <waddlesplash@gmail.com>
Date: Mon, 24 Jun 2024 15:38:26 -0400
Subject: [PATCH] file_systems/QueryParser: Limit to 32 equations maximum.

This way, we won't run into stack overflow issues due to recursion.
Who would really need a FS query with more than 32 equations, anyway?

Fixes #18692.

Change-Id: Ieda401446d9cae2e56100ddbab08bebcc724b484
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7789
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Haiku-Format: Haiku-format Bot <no-reply+haikuformatbot@haiku-os.org>
---
 headers/private/file_systems/QueryParser.h | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/headers/private/file_systems/QueryParser.h b/headers/private/file_systems/QueryParser.h
index 2933f0488c..5fcb90d3e6 100644
--- a/headers/private/file_systems/QueryParser.h
+++ b/headers/private/file_systems/QueryParser.h
@@ -1179,12 +1179,15 @@ Expression<QueryPolicy>::Init(const char* expr, const char** position)
 	if (fTerm != NULL)
 		return EALREADY;
 
+	status_t status = B_OK;
+	int32 equations = 0;
+	const int32 kMaxEquations = 32;
+
 	struct ExpressionNode {
 		Term<QueryPolicy>* term = NULL;
 		bool negated = false;
 		ops op = OP_NONE;
 	};
-	status_t status = B_OK;
 	Stack<Stack<ExpressionNode>*> exprsTree;
 	Stack<ExpressionNode>* currentExpr = NULL;
 	ExpressionNode* current = NULL;
@@ -1241,6 +1244,10 @@ Expression<QueryPolicy>::Init(const char* expr, const char** position)
 		} else if (!complete) {
 			if (current->term != NULL)
 				break; // There already is a term.
+			if ((equations + 1) > kMaxEquations) {
+				status = E2BIG;
+				break;
+			}
 
 			Equation<QueryPolicy>* equation
 				= new(std::nothrow) Equation<QueryPolicy>(&expr);
@@ -1255,6 +1262,7 @@ Expression<QueryPolicy>::Init(const char* expr, const char** position)
 			}
 
 			current->term = equation;
+			equations++;
 		}
 		if (!complete)
 			continue;