From 049c7f7a8e503f4a3f99104e4a3dd82637db226b Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Mon, 16 Nov 2020 20:12:25 +0100
Subject: [PATCH] Disallow using modifiers not in the current contract or in
 base contracts.

---
 libsolidity/analysis/TypeChecker.cpp                 | 12 ++++++++++++
 .../syntaxTests/modifiers/access_in_library.sol      |  9 +++++++++
 .../syntaxTests/modifiers/cross_contract_access.sol  |  9 +++++++++
 .../syntaxTests/modifiers/cross_contract_base.sol    |  8 ++++++++
 .../modifiers/cross_contract_unrelated.sol           | 11 +++++++++++
 .../syntaxTests/modifiers/library_via_using.sol      | 10 ++++++++++
 6 files changed, 59 insertions(+)
 create mode 100644 test/libsolidity/syntaxTests/modifiers/access_in_library.sol
 create mode 100644 test/libsolidity/syntaxTests/modifiers/cross_contract_access.sol
 create mode 100644 test/libsolidity/syntaxTests/modifiers/cross_contract_base.sol
 create mode 100644 test/libsolidity/syntaxTests/modifiers/cross_contract_unrelated.sol
 create mode 100644 test/libsolidity/syntaxTests/modifiers/library_via_using.sol

diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 5d9e23242..5d5d7a852 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -630,7 +630,19 @@ void TypeChecker::visitManually(
 	vector<ASTPointer<VariableDeclaration>> emptyParameterList;
 	vector<ASTPointer<VariableDeclaration>> const* parameters = nullptr;
 	if (auto modifierDecl = dynamic_cast<ModifierDefinition const*>(declaration))
+	{
 		parameters = &modifierDecl->parameters();
+		if (auto const* modifierContract = dynamic_cast<ContractDefinition const*>(modifierDecl->scope()))
+			if (m_currentContract)
+			{
+				if (!contains(m_currentContract->annotation().linearizedBaseContracts, modifierContract))
+					m_errorReporter.typeError(
+						9428_error,
+						_modifier.location(),
+						"Can only use modifiers defined in the current contract or in base contracts."
+					);
+			}
+	}
 	else
 		// check parameters for Base constructors
 		for (ContractDefinition const* base: _bases)
diff --git a/test/libsolidity/syntaxTests/modifiers/access_in_library.sol b/test/libsolidity/syntaxTests/modifiers/access_in_library.sol
new file mode 100644
index 000000000..052c60bde
--- /dev/null
+++ b/test/libsolidity/syntaxTests/modifiers/access_in_library.sol
@@ -0,0 +1,9 @@
+library L {
+    modifier m() { _; }
+}
+contract C {
+    function f() L.m public {
+    }
+}
+// ----
+// TypeError 9428: (68-71): Can only use modifiers defined in the current contract or in base contracts.
diff --git a/test/libsolidity/syntaxTests/modifiers/cross_contract_access.sol b/test/libsolidity/syntaxTests/modifiers/cross_contract_access.sol
new file mode 100644
index 000000000..430b8afe1
--- /dev/null
+++ b/test/libsolidity/syntaxTests/modifiers/cross_contract_access.sol
@@ -0,0 +1,9 @@
+contract C {
+    modifier m() { _; }
+}
+contract D {
+    function f() C.m public {
+    }
+}
+// ----
+// TypeError 9428: (69-72): Can only use modifiers defined in the current contract or in base contracts.
diff --git a/test/libsolidity/syntaxTests/modifiers/cross_contract_base.sol b/test/libsolidity/syntaxTests/modifiers/cross_contract_base.sol
new file mode 100644
index 000000000..391feb859
--- /dev/null
+++ b/test/libsolidity/syntaxTests/modifiers/cross_contract_base.sol
@@ -0,0 +1,8 @@
+contract C {
+    modifier m() { _; }
+}
+contract D is C {
+    function f() C.m public {
+    }
+}
+// ----
diff --git a/test/libsolidity/syntaxTests/modifiers/cross_contract_unrelated.sol b/test/libsolidity/syntaxTests/modifiers/cross_contract_unrelated.sol
new file mode 100644
index 000000000..7ca8b9ca2
--- /dev/null
+++ b/test/libsolidity/syntaxTests/modifiers/cross_contract_unrelated.sol
@@ -0,0 +1,11 @@
+contract A {}
+contract C is A {
+    modifier m() { _; }
+}
+contract D is A {
+    function f() C.m public {
+    }
+}
+contract T is D, C {}
+// ----
+// TypeError 9428: (93-96): Can only use modifiers defined in the current contract or in base contracts.
diff --git a/test/libsolidity/syntaxTests/modifiers/library_via_using.sol b/test/libsolidity/syntaxTests/modifiers/library_via_using.sol
new file mode 100644
index 000000000..bac0b33da
--- /dev/null
+++ b/test/libsolidity/syntaxTests/modifiers/library_via_using.sol
@@ -0,0 +1,10 @@
+library L {
+    modifier m() { _; }
+}
+contract C {
+    using L for *;
+    function f() L.m public {
+    }
+}
+// ----
+// TypeError 9428: (87-90): Can only use modifiers defined in the current contract or in base contracts.