https://github.com/MaskRay created
https://github.com/llvm/llvm-project/pull/85501
Linux kernel uses -fwrapv to change signed integer overflows from
undefined behaviors to defined behaviors. However, the security folks
still want -fsanitize=signed-integer-overflow diagnostics. Their
intention can be expressed with -fwrapv
-fsanitize=signed-integer-overflow (#80089). This mode by default
reports recoverable errors while still making signed integer overflows
defined (most UBSan checks are recoverable by default: you get errors in
stderr, but the program is not halted).
-fsanitize=undefined -fwrapv users likely want to suppress
signed-integer-overflow, unless signed-integer-overflow is explicitly
enabled. Implement this suppression.
>From d4cd5d737fbd686d54377584288ee336b95fe113 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i...@maskray.me>
Date: Fri, 15 Mar 2024 23:44:24 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
=?UTF-8?q?l=20version?=
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Created using spr 1.3.5-bogner
---
clang/lib/Driver/SanitizerArgs.cpp | 8 ++++++
.../fsanitize-signed-integer-overflow.c | 28 +++++++++++++++++++
2 files changed, 36 insertions(+)
create mode 100644 clang/test/Driver/fsanitize-signed-integer-overflow.c
diff --git a/clang/lib/Driver/SanitizerArgs.cpp
b/clang/lib/Driver/SanitizerArgs.cpp
index 56d497eb4c32b8..8bfe9f02a091d1 100644
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -487,6 +487,14 @@ SanitizerArgs::SanitizerArgs(const ToolChain &TC,
Add &= ~NotAllowedWithExecuteOnly;
if (CfiCrossDso)
Add &= ~SanitizerKind::CFIMFCall;
+ // -fsanitize=undefined does not expand to signed-integer-overflow in
+ // -fwrapv (implied by -fno-strict-overflow) mode.
+ if (Add & SanitizerKind::UndefinedGroup) {
+ bool S = Args.hasFlagNoClaim(options::OPT_fno_strict_overflow,
+ options::OPT_fstrict_overflow, false);
+ if (Args.hasFlagNoClaim(options::OPT_fwrapv, options::OPT_fno_wrapv,
S))
+ Add &= ~SanitizerKind::SignedIntegerOverflow;
+ }
Add &= Supported;
if (Add & SanitizerKind::Fuzzer)
diff --git a/clang/test/Driver/fsanitize-signed-integer-overflow.c
b/clang/test/Driver/fsanitize-signed-integer-overflow.c
new file mode 100644
index 00000000000000..4a9345493b6aa8
--- /dev/null
+++ b/clang/test/Driver/fsanitize-signed-integer-overflow.c
@@ -0,0 +1,28 @@
+/// When -fwrapv (implied by -fno-strict-overflow) is enabled,
+/// -fsanitize=undefined does not expand to signed-integer-overflow.
+/// -fsanitize=signed-integer-overflow is unaffected by -fwrapv.
+
+// RUN: %clang -### --target=x86_64-linux -fwrapv
-fsanitize=signed-integer-overflow %s 2>&1 | FileCheck %s
+// CHECK: -fsanitize=signed-integer-overflow
+// CHECK: -fsanitize-recover=signed-integer-overflow
+
+// RUN: %clang -### --target=x86_64-linux -fno-strict-overflow
-fsanitize=undefined %s 2>&1 | FileCheck %s --check-prefix=EXCLUDE
+// RUN: %clang -### --target=x86_64-linux -fstrict-overflow -fwrapv
-fsanitize=undefined %s 2>&1 | FileCheck %s --check-prefix=EXCLUDE
+// EXCLUDE: -fsanitize=alignment,array-bounds,
+// EXCLUDE-NOT: signed-integer-overflow,
+// EXCLUDE: -fsanitize-recover=alignment,array-bounds,
+// EXCLUDE-SAME: signed-integer-overflow
+
+// RUN: %clang -### --target=x86_64-linux -fwrapv -fsanitize=undefined
-fsanitize=signed-integer-overflow %s 2>&1 | FileCheck %s --check-prefix=INCLUDE
+// RUN: %clang -### --target=x86_64-linux -fno-strict-overflow
-fno-sanitize=signed-integer-overflow -fsanitize=undefined
-fsanitize=signed-integer-overflow %s 2>&1 | FileCheck %s --check-prefix=INCLUDE
+// INCLUDE: -fsanitize=alignment,array-bounds,
+// INCLUDE-SAME: signed-integer-overflow
+// INCLUDE: -fsanitize-recover=alignment,array-bounds,
+// INCLUDE-SAME: signed-integer-overflow
+
+/// -fsanitize-trap=undefined expands to signed-integer-overflow regardless of
-fwrapv.
+// RUN: %clang -### --target=x86_64-linux -fwrapv -fsanitize=undefined
-fsanitize=signed-integer-overflow -fsanitize-trap=undefined %s 2>&1 |
FileCheck %s --check-prefix=INCLUDE-TRAP
+// INCLUDE-TRAP: -fsanitize=alignment,array-bounds,
+// INCLUDE-TRAP-SAME: signed-integer-overflow
+// INCLUDE-TRAP: -fsanitize-trap=alignment,array-bounds,
+// INCLUDE-TRAP-SAME: signed-integer-overflow
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