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[clang][driver] Correcting arguments when using libFuzzer with -shared-libsan #164842

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[clang][driver] Correcting arguments when using libFuzzer with -shared-libsan #164842

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0a8665d
[clang][driver] Add required deps when using shared-libsan and fuzzer
bjosv Oct 23, 2025
1d57f99
[clang][driver] Correcting dependency order when using fuzzer
bjosv Oct 23, 2025
671b74b
fixup: filecheck w/o path separator to pass tests on Windows
bjosv Oct 24, 2025
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11 changes: 8 additions & 3 deletions clang/lib/Driver/ToolChains/CommonArgs.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1716,11 +1716,17 @@ 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() &&
!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);
Expand All @@ -1735,8 +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;
Expand Down Expand Up @@ -1769,7 +1773,8 @@ 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) {
Expand Down
8 changes: 7 additions & 1 deletion clang/test/Driver/fuzzer.c
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Expand Up @@ -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
Expand All @@ -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;
}
8 changes: 8 additions & 0 deletions clang/test/Driver/sanitizer-ld.c
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Expand Up @@ -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++"