https://github.com/tbaederr created
https://github.com/llvm/llvm-project/pull/119535
None
>From 03a5f354277a36d8380477bbd13a35484d701d3a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbae...@redhat.com>
Date: Wed, 11 Dec 2024 11:08:40 +0100
Subject: [PATCH] [clang][bytecode] Check for overlapping memcpy regions
---
clang/lib/AST/ByteCode/InterpBuiltin.cpp | 14 ++++++++++++++
clang/test/AST/ByteCode/builtin-functions.cpp | 15 +++++++++++++++
2 files changed, 29 insertions(+)
diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index a0de193ec32a2f..4fe17ec01906e9 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -1875,6 +1875,20 @@ static bool interp__builtin_memcpy(InterpState &S,
CodePtr OpPC,
return false;
}
+ // Check for overlapping memory regions.
+ if (!Move && SrcPtr.block() == DestPtr.block()) {
+ unsigned SrcIndex = SrcPtr.getIndex() * SrcPtr.elemSize();
+ unsigned DstIndex = DestPtr.getIndex() * DestPtr.elemSize();
+ unsigned N = Size.getZExtValue();
+
+ if ((SrcIndex <= DstIndex && (SrcIndex + N) > DstIndex) ||
+ (DstIndex <= SrcIndex && (DstIndex + N) > SrcIndex)) {
+ S.FFDiag(S.Current->getSource(OpPC), diag::note_constexpr_memcpy_overlap)
+ << /*IsWChar=*/false;
+ return false;
+ }
+ }
+
// As a last resort, reject dummy pointers.
if (DestPtr.isDummy() || SrcPtr.isDummy())
return false;
diff --git a/clang/test/AST/ByteCode/builtin-functions.cpp
b/clang/test/AST/ByteCode/builtin-functions.cpp
index 7dd08cb5fa1c35..ef6faae030a8f2 100644
--- a/clang/test/AST/ByteCode/builtin-functions.cpp
+++ b/clang/test/AST/ByteCode/builtin-functions.cpp
@@ -1207,4 +1207,19 @@ namespace BuiltinMemcpy {
}
static_assert(memcpyTypeRem() == 12); // both-error {{not an integral
constant expression}} \
// both-note {{in call to}}
+
+ template<typename T>
+ constexpr T result(T (&arr)[4]) {
+ return arr[0] * 1000 + arr[1] * 100 + arr[2] * 10 + arr[3];
+ }
+
+ constexpr int test_memcpy(int a, int b, int n) {
+ int arr[4] = {1, 2, 3, 4};
+ __builtin_memcpy(arr + a, arr + b, n); // both-note {{overlapping memory
regions}}
+ return result(arr);
+ }
+
+ static_assert(test_memcpy(1, 2, sizeof(int)) == 1334);
+ static_assert(test_memcpy(0, 1, sizeof(int) * 2) == 2334); // both-error
{{not an integral constant expression}} \
+ // both-note {{in
call}}
}
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