[compiler-rt] f78d9fc - [libFuzzer] Link libFuzzer's own interceptors when other compiler runtimes are not linked.
Matt Morehouse via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 16 13:26:48 PDT 2020
Author: Dokyung Song
Date: 2020-07-16T20:26:35Z
New Revision: f78d9fceea736d431e9e3cbca291e3909e3aa46d
URL: https://github.com/llvm/llvm-project/commit/f78d9fceea736d431e9e3cbca291e3909e3aa46d
DIFF: https://github.com/llvm/llvm-project/commit/f78d9fceea736d431e9e3cbca291e3909e3aa46d.diff
LOG: [libFuzzer] Link libFuzzer's own interceptors when other compiler runtimes are not linked.
Summary: libFuzzer intercepts certain library functions such as memcmp/strcmp by defining weak hooks. Weak hooks, however, are called only when other runtimes such as ASan is linked. This patch defines libFuzzer's own interceptors, which is linked into the libFuzzer executable when other runtimes are not linked, i.e., when -fsanitize=fuzzer is given, but not others.
Reviewers: kcc, morehouse, hctim
Reviewed By: morehouse, hctim
Subscribers: krytarowski, mgorny, cfe-commits, #sanitizers
Tags: #clang, #sanitizers
Differential Revision: https://reviews.llvm.org/D83494
Added:
compiler-rt/lib/fuzzer/FuzzerInterceptors.cpp
Modified:
clang/include/clang/Driver/SanitizerArgs.h
clang/lib/Driver/SanitizerArgs.cpp
clang/lib/Driver/ToolChains/CommonArgs.cpp
compiler-rt/lib/fuzzer/CMakeLists.txt
compiler-rt/test/fuzzer/memcmp.test
compiler-rt/test/fuzzer/memcmp64.test
compiler-rt/test/fuzzer/strcmp.test
compiler-rt/test/fuzzer/strncmp.test
compiler-rt/test/fuzzer/strstr.test
Removed:
################################################################################
diff --git a/clang/include/clang/Driver/SanitizerArgs.h b/clang/include/clang/Driver/SanitizerArgs.h
index 934dab808e82..563d6c3ff9de 100644
--- a/clang/include/clang/Driver/SanitizerArgs.h
+++ b/clang/include/clang/Driver/SanitizerArgs.h
@@ -74,6 +74,7 @@ class SanitizerArgs {
!Sanitizers.has(SanitizerKind::Address) &&
!Sanitizers.has(SanitizerKind::HWAddress);
}
+ bool needsFuzzerInterceptors() const;
bool needsUbsanRt() const;
bool requiresMinimalRuntime() const { return MinimalRuntime; }
bool needsDfsanRt() const { return Sanitizers.has(SanitizerKind::DataFlow); }
diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
index bcc9ffc7ff8f..e4fda752c041 100644
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -240,6 +240,10 @@ static SanitizerMask parseSanitizeTrapArgs(const Driver &D,
return TrappingKinds;
}
+bool SanitizerArgs::needsFuzzerInterceptors() const {
+ return needsFuzzer() && !needsAsanRt() && !needsTsanRt() && !needsMsanRt();
+}
+
bool SanitizerArgs::needsUbsanRt() const {
// All of these include ubsan.
if (needsAsanRt() || needsMsanRt() || needsHwasanRt() || needsTsanRt() ||
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 6b6e276b8ce7..acde6d9e2111 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -784,6 +784,9 @@ bool tools::addSanitizerRuntimes(const ToolChain &TC, const ArgList &Args,
!Args.hasArg(options::OPT_shared)) {
addSanitizerRuntime(TC, Args, CmdArgs, "fuzzer", false, true);
+ if (SanArgs.needsFuzzerInterceptors())
+ addSanitizerRuntime(TC, Args, CmdArgs, "fuzzer_interceptors", false,
+ true);
if (!Args.hasArg(clang::driver::options::OPT_nostdlibxx))
TC.AddCXXStdlibLibArgs(Args, CmdArgs);
}
diff --git a/compiler-rt/lib/fuzzer/CMakeLists.txt b/compiler-rt/lib/fuzzer/CMakeLists.txt
index b5be6b89452e..02be89cb70a5 100644
--- a/compiler-rt/lib/fuzzer/CMakeLists.txt
+++ b/compiler-rt/lib/fuzzer/CMakeLists.txt
@@ -99,6 +99,13 @@ add_compiler_rt_object_libraries(RTfuzzer_main
CFLAGS ${LIBFUZZER_CFLAGS}
DEPS ${LIBFUZZER_DEPS})
+add_compiler_rt_object_libraries(RTfuzzer_interceptors
+ OS ${FUZZER_SUPPORTED_OS}
+ ARCHS ${FUZZER_SUPPORTED_ARCH}
+ SOURCES FuzzerInterceptors.cpp
+ CFLAGS ${LIBFUZZER_CFLAGS}
+ DEPS ${LIBFUZZER_DEPS})
+
add_compiler_rt_runtime(clang_rt.fuzzer
STATIC
OS ${FUZZER_SUPPORTED_OS}
@@ -115,6 +122,14 @@ add_compiler_rt_runtime(clang_rt.fuzzer_no_main
CFLAGS ${LIBFUZZER_CFLAGS}
PARENT_TARGET fuzzer)
+add_compiler_rt_runtime(clang_rt.fuzzer_interceptors
+ STATIC
+ OS ${FUZZER_SUPPORTED_OS}
+ ARCHS ${FUZZER_SUPPORTED_ARCH}
+ OBJECT_LIBS RTfuzzer_interceptors
+ CFLAGS ${LIBFUZZER_CFLAGS}
+ PARENT_TARGET fuzzer)
+
if(OS_NAME MATCHES "Linux|Fuchsia" AND
COMPILER_RT_LIBCXX_PATH AND
COMPILER_RT_LIBCXXABI_PATH)
@@ -148,7 +163,10 @@ if(OS_NAME MATCHES "Linux|Fuchsia" AND
add_dependencies(RTfuzzer.${arch} libcxx_fuzzer_${arch}-build)
target_compile_options(RTfuzzer_main.${arch} PRIVATE -isystem ${LIBCXX_${arch}_PREFIX}/include/c++/v1)
add_dependencies(RTfuzzer_main.${arch} libcxx_fuzzer_${arch}-build)
+ target_compile_options(RTfuzzer_interceptors.${arch} PRIVATE -isystem ${LIBCXX_${arch}_PREFIX}/include/c++/v1)
+ add_dependencies(RTfuzzer_interceptors.${arch} libcxx_fuzzer_${arch}-build)
partially_link_libcxx(fuzzer_no_main ${LIBCXX_${arch}_PREFIX} ${arch})
+ partially_link_libcxx(fuzzer_interceptors ${LIBCXX_${arch}_PREFIX} ${arch})
partially_link_libcxx(fuzzer ${LIBCXX_${arch}_PREFIX} ${arch})
endforeach()
endif()
diff --git a/compiler-rt/lib/fuzzer/FuzzerInterceptors.cpp b/compiler-rt/lib/fuzzer/FuzzerInterceptors.cpp
new file mode 100644
index 000000000000..cb55b4af38fa
--- /dev/null
+++ b/compiler-rt/lib/fuzzer/FuzzerInterceptors.cpp
@@ -0,0 +1,170 @@
+//===-- FuzzerInterceptors.cpp --------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+// Intercept certain libc functions to aid fuzzing.
+// Linked only when other RTs that define their own interceptors are not linked.
+//===----------------------------------------------------------------------===//
+
+#include "FuzzerPlatform.h"
+
+#if LIBFUZZER_LINUX
+
+#define GET_CALLER_PC() __builtin_return_address(0)
+
+#define PTR_TO_REAL(x) real_##x
+#define REAL(x) __interception::PTR_TO_REAL(x)
+#define FUNC_TYPE(x) x##_type
+#define DEFINE_REAL(ret_type, func, ...) \
+ typedef ret_type (*FUNC_TYPE(func))(__VA_ARGS__); \
+ namespace __interception { \
+ FUNC_TYPE(func) PTR_TO_REAL(func); \
+ }
+
+#include <cassert>
+#include <cstdint>
+#include <dlfcn.h> // for dlsym()
+#include <sanitizer/common_interface_defs.h>
+
+static void *getFuncAddr(const char *name, uintptr_t wrapper_addr) {
+ void *addr = dlsym(RTLD_NEXT, name);
+ if (!addr) {
+ // If the lookup using RTLD_NEXT failed, the sanitizer runtime library is
+ // later in the library search order than the DSO that we are trying to
+ // intercept, which means that we cannot intercept this function. We still
+ // want the address of the real definition, though, so look it up using
+ // RTLD_DEFAULT.
+ addr = dlsym(RTLD_DEFAULT, name);
+
+ // In case `name' is not loaded, dlsym ends up finding the actual wrapper.
+ // We don't want to intercept the wrapper and have it point to itself.
+ if (reinterpret_cast<uintptr_t>(addr) == wrapper_addr)
+ addr = nullptr;
+ }
+ return addr;
+}
+
+static int FuzzerInited = 0;
+static bool FuzzerInitIsRunning;
+
+static void fuzzerInit();
+
+static void ensureFuzzerInited() {
+ assert(!FuzzerInitIsRunning);
+ if (!FuzzerInited) {
+ fuzzerInit();
+ }
+}
+
+extern "C" {
+
+DEFINE_REAL(int, memcmp, const void *, const void *, size_t)
+DEFINE_REAL(int, strncmp, const char *, const char *, size_t)
+DEFINE_REAL(int, strcmp, const char *, const char *)
+DEFINE_REAL(int, strncasecmp, const char *, const char *, size_t)
+DEFINE_REAL(int, strcasecmp, const char *, const char *)
+DEFINE_REAL(char *, strstr, const char *, const char *)
+DEFINE_REAL(char *, strcasestr, const char *, const char *)
+DEFINE_REAL(void *, memmem, const void *, size_t, const void *, size_t)
+
+ATTRIBUTE_INTERFACE int memcmp(const void *s1, const void *s2, size_t n) {
+ ensureFuzzerInited();
+ int result = REAL(memcmp)(s1, s2, n);
+ __sanitizer_weak_hook_memcmp(GET_CALLER_PC(), s1, s2, n, result);
+
+ return result;
+}
+
+ATTRIBUTE_INTERFACE int strncmp(const char *s1, const char *s2, size_t n) {
+ ensureFuzzerInited();
+ int result = REAL(strncmp)(s1, s2, n);
+ __sanitizer_weak_hook_strncmp(GET_CALLER_PC(), s1, s2, n, result);
+
+ return result;
+}
+
+ATTRIBUTE_INTERFACE int strcmp(const char *s1, const char *s2) {
+ ensureFuzzerInited();
+ int result = REAL(strcmp)(s1, s2);
+ __sanitizer_weak_hook_strcmp(GET_CALLER_PC(), s1, s2, result);
+
+ return result;
+}
+
+ATTRIBUTE_INTERFACE int strncasecmp(const char *s1, const char *s2, size_t n) {
+ ensureFuzzerInited();
+ int result = REAL(strncasecmp)(s1, s2, n);
+ __sanitizer_weak_hook_strncasecmp(GET_CALLER_PC(), s1, s2, n, result);
+
+ return result;
+}
+
+ATTRIBUTE_INTERFACE int strcasecmp(const char *s1, const char *s2) {
+ ensureFuzzerInited();
+ int result = REAL(strcasecmp)(s1, s2);
+ __sanitizer_weak_hook_strcasecmp(GET_CALLER_PC(), s1, s2, result);
+
+ return result;
+}
+
+ATTRIBUTE_INTERFACE char *strstr(const char *s1, const char *s2) {
+ ensureFuzzerInited();
+ char *result = REAL(strstr)(s1, s2);
+ __sanitizer_weak_hook_strstr(GET_CALLER_PC(), s1, s2, result);
+
+ return result;
+}
+
+ATTRIBUTE_INTERFACE char *strcasestr(const char *s1, const char *s2) {
+ ensureFuzzerInited();
+ char *result = REAL(strcasestr)(s1, s2);
+ __sanitizer_weak_hook_strcasestr(GET_CALLER_PC(), s1, s2, result);
+
+ return result;
+}
+
+ATTRIBUTE_INTERFACE
+void *memmem(const void *s1, size_t len1, const void *s2, size_t len2) {
+ ensureFuzzerInited();
+ void *result = REAL(memmem)(s1, len1, s2, len2);
+ __sanitizer_weak_hook_memmem(GET_CALLER_PC(), s1, len1, s2, len2, result);
+
+ return result;
+}
+
+__attribute__((section(".preinit_array"),
+ used)) static void (*__local_fuzzer_preinit)(void) = fuzzerInit;
+
+} // extern "C"
+
+static void fuzzerInit() {
+ assert(!FuzzerInitIsRunning);
+ if (FuzzerInited)
+ return;
+ FuzzerInitIsRunning = true;
+
+ REAL(memcmp) = reinterpret_cast<memcmp_type>(
+ getFuncAddr("memcmp", reinterpret_cast<uintptr_t>(&memcmp)));
+ REAL(strncmp) = reinterpret_cast<strncmp_type>(
+ getFuncAddr("strncmp", reinterpret_cast<uintptr_t>(&strncmp)));
+ REAL(strcmp) = reinterpret_cast<strcmp_type>(
+ getFuncAddr("strcmp", reinterpret_cast<uintptr_t>(&strcmp)));
+ REAL(strncasecmp) = reinterpret_cast<strncasecmp_type>(
+ getFuncAddr("strncasecmp", reinterpret_cast<uintptr_t>(&strncasecmp)));
+ REAL(strcasecmp) = reinterpret_cast<strcasecmp_type>(
+ getFuncAddr("strcasecmp", reinterpret_cast<uintptr_t>(&strcasecmp)));
+ REAL(strstr) = reinterpret_cast<strstr_type>(
+ getFuncAddr("strstr", reinterpret_cast<uintptr_t>(&strstr)));
+ REAL(strcasestr) = reinterpret_cast<strcasestr_type>(
+ getFuncAddr("strcasestr", reinterpret_cast<uintptr_t>(&strcasestr)));
+ REAL(memmem) = reinterpret_cast<memmem_type>(
+ getFuncAddr("memmem", reinterpret_cast<uintptr_t>(&memmem)));
+
+ FuzzerInitIsRunning = false;
+ FuzzerInited = 1;
+}
+
+#endif
diff --git a/compiler-rt/test/fuzzer/memcmp.test b/compiler-rt/test/fuzzer/memcmp.test
index 5657cab41dfc..8859afbe8a97 100644
--- a/compiler-rt/test/fuzzer/memcmp.test
+++ b/compiler-rt/test/fuzzer/memcmp.test
@@ -1,4 +1,8 @@
UNSUPPORTED: freebsd
RUN: %cpp_compiler %S/MemcmpTest.cpp -o %t-MemcmpTest
RUN: not %run %t-MemcmpTest -seed=1 -runs=10000000 2>&1 | FileCheck %s
+
+RUN: %cpp_compiler -fno-sanitize=address -fno-builtin-memcmp %S/MemcmpTest.cpp -o %t-NoAsanMemcmpTest
+RUN: not %run %t-MemcmpTest -seed=1 -runs=10000000 2>&1 | FileCheck %s
+
CHECK: BINGO
diff --git a/compiler-rt/test/fuzzer/memcmp64.test b/compiler-rt/test/fuzzer/memcmp64.test
index 24d14bf73bbf..fc9d02324373 100644
--- a/compiler-rt/test/fuzzer/memcmp64.test
+++ b/compiler-rt/test/fuzzer/memcmp64.test
@@ -1,4 +1,8 @@
UNSUPPORTED: freebsd
RUN: %cpp_compiler %S/Memcmp64BytesTest.cpp -o %t-Memcmp64BytesTest
RUN: not %run %t-Memcmp64BytesTest -seed=1 -runs=1000000 2>&1 | FileCheck %s
+
+RUN: %cpp_compiler -fno-sanitize=address -fno-builtin-memcmp %S/Memcmp64BytesTest.cpp -o %t-NoAsanMemcmp64BytesTest
+RUN: not %run %t-Memcmp64BytesTest -seed=1 -runs=1000000 2>&1 | FileCheck %s
+
CHECK: BINGO
diff --git a/compiler-rt/test/fuzzer/strcmp.test b/compiler-rt/test/fuzzer/strcmp.test
index bd917bba6b69..eebcf8ef5c70 100644
--- a/compiler-rt/test/fuzzer/strcmp.test
+++ b/compiler-rt/test/fuzzer/strcmp.test
@@ -1,5 +1,8 @@
UNSUPPORTED: freebsd
RUN: %cpp_compiler %S/StrcmpTest.cpp -o %t-StrcmpTest
RUN: not %run %t-StrcmpTest -seed=1 -runs=2000000 2>&1 | FileCheck %s
-CHECK: BINGO
+RUN: %cpp_compiler -fno-sanitize=address -fno-builtin-strcmp %S/StrcmpTest.cpp -o %t-NoAsanStrcmpTest
+RUN: not %run %t-StrcmpTest -seed=1 -runs=2000000 2>&1 | FileCheck %s
+
+CHECK: BINGO
diff --git a/compiler-rt/test/fuzzer/strncmp.test b/compiler-rt/test/fuzzer/strncmp.test
index 50189445b102..f8ff9299a1d9 100644
--- a/compiler-rt/test/fuzzer/strncmp.test
+++ b/compiler-rt/test/fuzzer/strncmp.test
@@ -1,5 +1,8 @@
UNSUPPORTED: freebsd
RUN: %cpp_compiler %S/StrncmpTest.cpp -o %t-StrncmpTest
RUN: not %run %t-StrncmpTest -seed=2 -runs=10000000 2>&1 | FileCheck %s
-CHECK: BINGO
+RUN: %cpp_compiler -fno-sanitize=address -fno-builtin-strncmp %S/StrncmpTest.cpp -o %t-NoAsanStrncmpTest
+RUN: not %run %t-StrncmpTest -seed=2 -runs=10000000 2>&1 | FileCheck %s
+
+CHECK: BINGO
diff --git a/compiler-rt/test/fuzzer/strstr.test b/compiler-rt/test/fuzzer/strstr.test
index f1fb210b47c7..54a5abe8a414 100644
--- a/compiler-rt/test/fuzzer/strstr.test
+++ b/compiler-rt/test/fuzzer/strstr.test
@@ -1,5 +1,8 @@
UNSUPPORTED: freebsd
RUN: %cpp_compiler %S/StrstrTest.cpp -o %t-StrstrTest
RUN: not %run %t-StrstrTest -seed=1 -runs=2000000 2>&1 | FileCheck %s
-CHECK: BINGO
+RUN: %cpp_compiler -fno-sanitize=address -fno-builtin-strstr %S/StrstrTest.cpp -o %t-NoAsanStrstrTest
+RUN: not %run %t-StrstrTest -seed=1 -runs=2000000 2>&1 | FileCheck %s
+
+CHECK: BINGO
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