https://github.com/bjosv created
https://github.com/llvm/llvm-project/pull/164842
This PR contains two commits:
- Add required dependencies when using `-shared-libsan` and fuzzer.
Since libFuzzer is a static library we need to make sure that we add its
dependencies when building with `-shared-libsan`. E.g libFuzzer uses `ceilf()`
from `libm.so` when building on Gnu toolchain.
Previously, the resulting command did not contain the required link libraries,
giving build failures
(only a static sanitizer runtime would trigger the call to
`linkSanitizerRuntimeDeps`).
- Correcting dependency order when using fuzzer.
When building using `-shared-libsan` the sanitizer library needs to be first in
link order.
Since the fuzzer requires `-lstdc++` we have to make sure that the sanitizer
library is added before `-lstdc++`.
From 0a8665ddfee946ab060c8d115db666901a58f70d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Svensson?= <[email protected]>
Date: Thu, 23 Oct 2025 15:54:17 +0200
Subject: [PATCH 1/2] [clang][driver] Add required deps when using
shared-libsan and fuzzer
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Since libFuzzer is a static library we need to make sure we add its
dependencies when building with '-shared-libsan'.
E.g libFuzzer uses ceilf() from libm.so when building on Gnu toolchain.
Previously, the resulting command did not contain the required
link libraries, giving build failures.
Signed-off-by: Björn Svensson <[email protected]>
---
clang/lib/Driver/ToolChains/CommonArgs.cpp | 5 ++++-
clang/test/Driver/fuzzer.c | 8 +++++++-
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 99400ac701fbe..1b746b3426ead 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1717,10 +1717,12 @@ bool tools::addSanitizerRuntimes(const ToolChain &TC,
const ArgList &Args,
}
// Inject libfuzzer dependencies.
+ bool FuzzerNeedsSanitizerDeps = false;
if (SanArgs.needsFuzzer() && SanArgs.linkRuntimes() &&
!Args.hasArg(options::OPT_shared)) {
addSanitizerRuntime(TC, Args, CmdArgs, "fuzzer", false, true);
+ FuzzerNeedsSanitizerDeps = true;
if (SanArgs.needsFuzzerInterceptors())
addSanitizerRuntime(TC, Args, CmdArgs, "fuzzer_interceptors", false,
true);
@@ -1769,7 +1771,8 @@ bool tools::addSanitizerRuntimes(const ToolChain &TC,
const ArgList &Args,
CmdArgs.push_back("--android-memtag-stack");
}
- return !StaticRuntimes.empty() || !NonWholeStaticRuntimes.empty();
+ return !StaticRuntimes.empty() || !NonWholeStaticRuntimes.empty() ||
+ FuzzerNeedsSanitizerDeps;
}
bool tools::addXRayRuntime(const ToolChain&TC, const ArgList &Args,
ArgStringList &CmdArgs) {
diff --git a/clang/test/Driver/fuzzer.c b/clang/test/Driver/fuzzer.c
index 409fbfac8ce1d..8ca7f32bf4d8e 100644
--- a/clang/test/Driver/fuzzer.c
+++ b/clang/test/Driver/fuzzer.c
@@ -26,7 +26,7 @@
// CHECK-NOLIB-NOT: libclang_rt.libfuzzer
// CHECK-COV: -fsanitize-coverage-inline-8bit-counters
-// Check that we respect whether thes tandard library should be linked
+// Check that we respect whether the standard library should be linked.
// statically.
//
// RUN: %clang -fsanitize=fuzzer --target=i386-unknown-linux -stdlib=libstdc++
%s -### 2>&1 | FileCheck --check-prefixes=CHECK-LIBSTDCXX-DYNAMIC %s
@@ -43,6 +43,12 @@
// RUN: %clang -fsanitize=fuzzer --target=i386-unknown-linux -stdlib=libc++
-static-libstdc++ %s -### 2>&1 | FileCheck --check-prefixes=CHECK-LIBCXX-STATIC
%s
// CHECK-LIBCXX-STATIC: "-Bstatic" "-lc++"
+// Check that we add required sanitizer dependencies when dynamically linking
+// the sanitizer runtime (e.g. libFuzzer uses ceilf in libm).
+//
+// RUN: %clang -fsanitize=fuzzer -shared-libsan --target=x86_64-linux-gnu %s
-### 2>&1 | FileCheck --check-prefixes=CHECK-SHARED-LIBSAN %s
+// CHECK-SHARED-LIBSAN: -lm
+
int LLVMFuzzerTestOneInput(const char *Data, long Size) {
return 0;
}
From 1d57f9990abc4837183b2d1d74362b06c04f78e5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Svensson?= <[email protected]>
Date: Thu, 23 Oct 2025 17:52:06 +0200
Subject: [PATCH 2/2] [clang][driver] Correcting dependency order when using
fuzzer
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
When building using "-shared-libsan" the sanitizer library needs to
be first in link order. Since the fuzzer requires -lstdc++ we have
to make sure the sanitizer library is added before -lstdc++.
Signed-off-by: Björn Svensson <[email protected]>
---
clang/lib/Driver/ToolChains/CommonArgs.cpp | 6 ++++--
clang/test/Driver/sanitizer-ld.c | 8 ++++++++
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp
b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 1b746b3426ead..bbd30b83ccefd 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1716,6 +1716,10 @@ bool tools::addSanitizerRuntimes(const ToolChain &TC,
const ArgList &Args,
CmdArgs.push_back(Args.MakeArgString(S));
}
+ // Add shared runtimes before adding fuzzer and its dependencies.
+ for (auto RT : SharedRuntimes)
+ addSanitizerRuntime(TC, Args, CmdArgs, RT, true, false);
+
// Inject libfuzzer dependencies.
bool FuzzerNeedsSanitizerDeps = false;
if (SanArgs.needsFuzzer() && SanArgs.linkRuntimes() &&
@@ -1737,8 +1741,6 @@ bool tools::addSanitizerRuntimes(const ToolChain &TC,
const ArgList &Args,
}
}
- for (auto RT : SharedRuntimes)
- addSanitizerRuntime(TC, Args, CmdArgs, RT, true, false);
for (auto RT : HelperStaticRuntimes)
addSanitizerRuntime(TC, Args, CmdArgs, RT, false, true);
bool AddExportDynamic = false;
diff --git a/clang/test/Driver/sanitizer-ld.c b/clang/test/Driver/sanitizer-ld.c
index ac1851286af63..89003b4e10ccd 100644
--- a/clang/test/Driver/sanitizer-ld.c
+++ b/clang/test/Driver/sanitizer-ld.c
@@ -1393,3 +1393,11 @@
// RUN: | %{filecheck} --check-prefix=CHECK-RELOCATABLE-LINK-TSAN-RTLIB
//
// CHECK-RELOCATABLE-LINK-TSAN-RTLIB-NOT: "{{.*}}tsan{{.*}}"
+
+// RUN: %clang -fsanitize=fuzzer,address -shared-libsan -### %s 2>&1 \
+// RUN: --target=x86_64-unknown-linux -fuse-ld=ld \
+// RUN: -resource-dir=%S/Inputs/resource_dir \
+// RUN: --sysroot=%S/Inputs/basic_linux_tree \
+// RUN: | FileCheck %s --check-prefix=CHECK-FUZZER-WITH-SHARED-ASAN-ORDER
+//
+// CHECK-FUZZER-WITH-SHARED-ASAN-ORDER: "{{.*}}/libclang_rt.asan.so"
"--whole-archive" "{{.*}}/libclang_rt.fuzzer.a" "--no-whole-archive" "-lstdc++"
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