[NOT FOR COMMIT] Reproducer for mis-compiled exception handling

The corresponding github issue has more detail on the problem. This code is not in any meaningful state to be committed -- it contains a bunch of hacks I had to make to get the binary to build statically -- libunwind is linked in (via folly), and I had to make changes to include liblzma as well (which libunwind depends on) as well as fix some other unrelated cmake issues. Reproduction instructions below. First, build it with `python infra/helper.py build_fuzzers --sanitizer address proxygen` Then, check the build (it will pass): `python infra/helper.py check_build proxygen` Then, run the fuzzer: `python infra/helper.py run_fuzzer proxygen ProxygenHTTP1xFuzzer` It will fail in about ~30 seconds with the below trace. If the fuzzer goes down another path, I've had it reproduce easily by pulling up the shell, running `base64 -d`, pushing that input to a file, and then running the fuzzer directly on that file. ``` terminating with uncaught exception of type folly::ConversionError: Non-digit character found: "OPY" AddressSanitizer:DEADLYSIGNAL ================================================================= ==11==ERROR: AddressSanitizer: ABRT on unknown address 0x00000000000b (pc 0x7fc166eb7428 bp 0x000000000001 sp 0x7ffcff0a6c78 T0) SCARINESS: 10 (signal) #0 0x7fc166eb7427 in gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x35427) google#1 0x7fc166eb9029 in abort (/lib/x86_64-linux-gnu/libc.so.6+0x37029) google#2 0x9ab7fa in abort_message (/out/ProxygenHTTP1xFuzzer+0x9ab7fa) google#3 0x9b009d in demangling_terminate_handler() (/out/ProxygenHTTP1xFuzzer+0x9b009d) google#4 0x9ab282 in std::__terminate(void (*)()) (/out/ProxygenHTTP1xFuzzer+0x9ab282) google#5 0x9adebd in __cxxabiv1::call_terminate(bool, _Unwind_Exception*) (/out/ProxygenHTTP1xFuzzer+0x9adebd) google#6 0x9ade60 in __cxxabiv1::scan_eh_tab(__cxxabiv1::(anonymous namespace)::scan_results&, _Unwind_Action, bool, _Unwind_Exception*, _Unwind_Context*) (/out/ProxygenHTTP1xFuzzer+0x9ade60) google#7 0x9ad5c6 in __gxx_personality_v0 (/out/ProxygenHTTP1xFuzzer+0x9ad5c6) google#8 0x7fc16725c262 in _Unwind_RaiseException (/lib/x86_64-linux-gnu/libgcc_s.so.1+0x10262) google#9 0x9acfd6 in __cxa_throw (/out/ProxygenHTTP1xFuzzer+0x9acfd6) google#10 0x5cedab in void folly::throw_exception<folly::ConversionError>(folly::ConversionError&&) /src/proxygen/proxygen/_build/deps/include/folly/lang/Exception.h:36:3 google#11 0x5eea03 in _ZZN5folly2toItEENSt3__19enable_ifIXntsr3std7is_sameINS_5RangeIPKcEET_EE5valueES7_E4typeES6_ENKUlNS_14ConversionCodeEE_clESA_ /src/proxygen/proxygen/_build/deps/include/folly/Conv.h:1581:26 google#12 0x5eea03 in _ZN5folly15expected_detail30expected_detail_ExpectedHelper14ExpectedHelper12thenOrThrow_IRNS0_15ExpectedStorageINS_5RangeIPKcEENS_14ConversionCodeELNS0_11StorageTypeE1EEENS_6detail18CheckTrailingSpaceEZNS_2toItEENSt3__19enable_ifIXntsr3std7is_sameIS8_T_EE5valueESI_E4typeES8_EUlS9_E_NS_8ExpectedINS_4UnitES9_EEvLb0ELi0EEET2_OSI_OT0_OT1_ /src/proxygen/proxygen/_build/deps/include/folly/Expected.h:610:5 google#13 0x5ed846 in _ZNR5folly8ExpectedINS_5RangeIPKcEENS_14ConversionCodeEE11thenOrThrowINS_6detail18CheckTrailingSpaceEZNS_2toItEENSt3__19enable_ifIXntsr3std7is_sameIS4_T_EE5valueESD_E4typeES4_EUlS5_E_EEDTclclsr3stdE7declvalISD_EEclL_ZNSB_7declvalIRS4_EEDTclsr3std3__1E9__declvalISD_ELi0EEEvEEEEOSD_OT0_ /src/proxygen/proxygen/_build/deps/include/folly/Expected.h:1226:16 google#14 0x5ed846 in _ZN5folly2toItEENSt3__19enable_ifIXntsr3std7is_sameINS_5RangeIPKcEET_EE5valueES7_E4typeES6_ /src/proxygen/proxygen/_build/deps/include/folly/Conv.h:1579:8 google#15 0x5ed445 in proxygen::ParseURL::parseAuthority() /src/proxygen/proxygen/lib/utils/ParseURL.cpp:155:15 google#16 0x5ec5e9 in proxygen::ParseURL::parseNonFully() /src/proxygen/proxygen/lib/utils/ParseURL.cpp:140:8 google#17 0x5ea87a in proxygen::ParseURL::parse() /src/proxygen/proxygen/lib/utils/ParseURL.cpp:96:5 google#18 0x59a99c in proxygen::ParseURL::init(folly::Range<char const*>) /src/proxygen/proxygen/lib/utils/ParseURL.h:34:5 google#19 0x58add1 in proxygen::ParseURL::ParseURL(folly::Range<char const*>) /src/proxygen/proxygen/lib/utils/ParseURL.h:28:5 google#20 0x58add1 in proxygen::ParseURL proxygen::HTTPMessage::setURL<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > >(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >&&) /src/proxygen/proxygen/lib/http/HTTPMessage.h:202:14 google#21 0x5795f0 in proxygen::HTTP1xCodec::onHeadersComplete(unsigned long) /src/proxygen/proxygen/lib/http/codec/HTTP1xCodec.cpp:976:31 google#22 0x58e2a3 in proxygen::HTTP1xCodec::onHeadersCompleteCB(proxygen::http_parser*, char const*, unsigned long) /src/proxygen/proxygen/lib/http/codec/HTTP1xCodec.cpp:1315:19 google#23 0x5f2222 in proxygen::http_parser_execute(proxygen::http_parser*, proxygen::http_parser_settings const*, char const*, unsigned long) /src/proxygen/proxygen/external/http_parser/http_parser_cpp.cpp:1868:17 google#24 0x577783 in proxygen::HTTP1xCodec::onIngress(folly::IOBuf const&) /src/proxygen/proxygen/lib/http/codec/HTTP1xCodec.cpp:200:26 google#25 0x55b728 in unsigned long proxygen::parse<proxygen::HTTP1xCodec>(proxygen::HTTP1xCodec*, unsigned char const*, unsigned int, int, std::__1::function<bool ()>) /src/proxygen/proxygen/lib/http/codec/test/TestUtils.h:57:23 google#26 0x55a6ef in LLVMFuzzerTestOneInput /src/proxygen/proxygen/fuzzers/ProxygenHTTP1xFuzzer.cpp:23:3 google#27 0x460771 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm/projects/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:554:15 google#28 0x45fe95 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool*) /src/llvm/projects/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:470:3 google#29 0x462247 in fuzzer::Fuzzer::MutateAndTestOne() /src/llvm/projects/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:696:19 google#30 0x462fe5 in fuzzer::Fuzzer::Loop(std::Fuzzer::vector<fuzzer::SizedFile, fuzzer::fuzzer_allocator<fuzzer::SizedFile> >&) /src/llvm/projects/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:832:5 google#31 0x450dd8 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm/projects/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:825:6 google#32 0x47b442 in main /src/llvm/projects/compiler-rt/lib/fuzzer/FuzzerMain.cpp:19:10 google#33 0x7fc166ea282f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f) google#34 0x424468 in _start (/out/ProxygenHTTP1xFuzzer+0x424468) AddressSanitizer can not provide additional info. SUMMARY: AddressSanitizer: ABRT (/lib/x86_64-linux-gnu/libc.so.6+0x35427) in gsignal ==11==ABORTING MS: 3 CrossOver-ChangeBit-EraseBytes-; base unit: 467e3fbf38770044dea566169b84c60cb269c89a 0x43,0x4f,0x50,0x59,0x20,0x43,0x3a,0x4f,0x50,0x59,0x2f,0x4f,0xff,0xa,0x43,0x4f,0x50,0x59,0x20,0x2f,0x4f,0xff,0xa,0x43,0x4f,0x50,0x59,0x20,0x2f,0x6f,0x20,0xff,0x50,0x59,0x0,0x43,0xcf,0x50,0x59,0xff,0x4f,0x50,0x33, COPY C:OPY/O\xff\x0aCOPY /O\xff\x0aCOPY /o \xffPY\x00C\xcfPY\xffOP3 artifact_prefix='./'; Test unit written to ./crash-2cd12847d55ebf08ec2eaee4e814c52e545e7f92 Base64: Q09QWSBDOk9QWS9P/wpDT1BZIC9P/wpDT1BZIC9vIP9QWQBDz1BZ/09QMw== ``` This seems wrong to me since the code is inside a try/catch block: https://github.com/facebook/proxygen/blob/master/proxygen/lib/utils/ParseURL.cpp#L159-L164 I can confirm that the same input does not crash the fuzzer in the version being built on oss-fuzz trunk (and indeed it would have also reported this as a test-case by now given it's been running over a day)
mhlakhani · Sep 25, 2019 · 6ee029d · 6ee029d
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diff --git a/projects/proxygen/Dockerfile b/projects/proxygen/Dockerfile
@@ -140,4 +140,8 @@ RUN apt-get install patchelf
 # Fetch source and copy over files
 RUN git clone --depth 1 https://github.com/facebook/proxygen.git proxygen
 WORKDIR proxygen
+COPY patch.txt .
+COPY folly_patch.txt ./proxygen/
+COPY fizz_patch.txt ./proxygen/
+RUN git apply ./patch.txt
 COPY build.sh $SRC/
diff --git a/projects/proxygen/build.sh b/projects/proxygen/build.sh
@@ -17,18 +17,8 @@
 
 cd proxygen
 
-# Link to, and copy over, libunwind
-# We need to link to libunwind to ensure exception handling works
-# See https://clang.llvm.org/docs/Toolchain.html#unwind-library
-export LDFLAGS="-lunwind"
-mkdir -p $OUT/lib
-cp /usr/lib/x86_64-linux-gnu/libunwind.so.8 $OUT/lib/
-
 # Build everything
 ./build.sh -m --no-install-dependencies --build-for-fuzzing
 
-# Patch rpath so fuzzers can find libunwind
-find ./_build/proxygen/fuzzers -type f -executable -exec patchelf --set-rpath '$ORIGIN/lib' {} \;
-
 # Copy fuzzers over to the destination
-find ./_build/proxygen/fuzzers -type f -executable -exec cp {} $OUT/ \;
+find ./_build/proxygen/fuzzers -type f -executable -exec cp {} $OUT/ \;
diff --git a/projects/proxygen/fizz_patch.txt b/projects/proxygen/fizz_patch.txt
@@ -0,0 +1,297 @@
+diff --git a/fizz/CMakeLists.txt b/fizz/CMakeLists.txt
+index 2ceaf70..5d55e1f 100644
+--- a/fizz/CMakeLists.txt
++++ b/fizz/CMakeLists.txt
+@@ -293,77 +293,78 @@ ELSE(CMAKE_CROSSCOMPILING)
+ ENDIF(CMAKE_CROSSCOMPILING)
+
+ SET(FIZZ_TEST_INSTALL_PREFIX ${CMAKE_INSTALL_PREFIX})
+-if(BUILD_TESTS)
+-  enable_testing()
+
+-  find_package(GMock REQUIRED)
+-  if(NOT LIBGMOCK_FOUND)
+-    include(ExternalProject)
+-
+-    # Download and install GoogleMock
+-    ExternalProject_Add(
+-        gtest
+-        GIT_REPOSITORY https://github.com/google/googletest.git
+-        GIT_TAG release-1.8.0
+-        PREFIX gtest
+-        # Disable install step
+-        INSTALL_COMMAND ""
+-        LOG_DOWNLOAD ON
+-        LOG_UPDATE 1
+-        LOG_CONFIGURE ON
+-        LOG_BUILD ON
+-        LOG_TEST 1
+-        LOG_INSTALL 1
+-    )
+-
+-    # Create a libgmock target to be used as a dependency by test programs
+-    add_library(libgmock IMPORTED STATIC GLOBAL)
+-    add_dependencies(libgmock gtest)
+-    add_library(libgmock_main IMPORTED STATIC GLOBAL)
+-    add_dependencies(libgmock_main gtest)
+-
+-    # Set gmock properties
+-    ExternalProject_Get_Property(gtest source_dir binary_dir)
+-    set_target_properties(libgmock PROPERTIES
+-        "IMPORTED_LOCATION" "${binary_dir}/googlemock/libgmock.a"
+-        "IMPORTED_LINK_INTERFACE_LIBRARIES" "${CMAKE_THREAD_LIBS_INIT}"
+-    )
+-    set_target_properties(libgmock_main PROPERTIES
+-        "IMPORTED_LOCATION" "${binary_dir}/googlemock/libgmock_main.a"
+-        "IMPORTED_LINK_INTERFACE_LIBRARIES" "${CMAKE_THREAD_LIBS_INIT}"
+-    )
+-    set(LIBGMOCK_LIBRARIES libgmock libgmock_main)
+-    set(LIBGMOCK_INCLUDE_DIR "${source_dir}/googlemock/include")
+-    set(LIBGTEST_INCLUDE_DIR "${source_dir}/googletest/include")
+-  endif()
++find_package(GMock REQUIRED)
++if(NOT LIBGMOCK_FOUND)
++include(ExternalProject)
++
++# Download and install GoogleMock
++ExternalProject_Add(
++gtest
++GIT_REPOSITORY https://github.com/google/googletest.git
++GIT_TAG release-1.8.0
++PREFIX gtest
++# Disable install step
++INSTALL_COMMAND ""
++LOG_DOWNLOAD ON
++LOG_UPDATE 1
++LOG_CONFIGURE ON
++LOG_BUILD ON
++LOG_TEST 1
++LOG_INSTALL 1
++)
+
+-  add_library(fizz_test_support
+-    crypto/aead/test/TestUtil.cpp
+-    crypto/test/TestUtil.cpp
+-    ${FIZZ_TEST_HEADERS})
++# Create a libgmock target to be used as a dependency by test programs
++add_library(libgmock IMPORTED STATIC GLOBAL)
++add_dependencies(libgmock gtest)
++add_library(libgmock_main IMPORTED STATIC GLOBAL)
++add_dependencies(libgmock_main gtest)
++
++# Set gmock properties
++ExternalProject_Get_Property(gtest source_dir binary_dir)
++set_target_properties(libgmock PROPERTIES
++"IMPORTED_LOCATION" "${binary_dir}/googlemock/libgmock.a"
++"IMPORTED_LINK_INTERFACE_LIBRARIES" "${CMAKE_THREAD_LIBS_INIT}"
++)
++set_target_properties(libgmock_main PROPERTIES
++"IMPORTED_LOCATION" "${binary_dir}/googlemock/libgmock_main.a"
++"IMPORTED_LINK_INTERFACE_LIBRARIES" "${CMAKE_THREAD_LIBS_INIT}"
++)
++set(LIBGMOCK_LIBRARIES libgmock libgmock_main)
++set(LIBGMOCK_INCLUDE_DIR "${source_dir}/googlemock/include")
++set(LIBGTEST_INCLUDE_DIR "${source_dir}/googletest/include")
++endif()
+
+-  target_link_libraries(fizz_test_support
+-    PUBLIC
+-      fizz
+-  )
+-
+-  # export fizz headers and targets for unit tests utils
+-  # since other projects such as mvfst and proxygen use them
+-  install(
+-    TARGETS fizz_test_support
+-    EXPORT fizz-exports
+-    ARCHIVE DESTINATION ${FIZZ_TEST_INSTALL_PREFIX}/lib
+-    LIBRARY DESTINATION ${FIZZ_TEST_INSTALL_PREFIX}/lib
+-  )
+-
+-  foreach(dir ${FIZZ_TEST_HEADER_DIRS})
+-    get_filename_component(PARENT_DIR "/${dir}" DIRECTORY)
+-    install(
+-      DIRECTORY ${dir}
+-      DESTINATION "${FIZZ_TEST_INSTALL_PREFIX}/include/fizz${PARENT_DIR}"
+-      FILES_MATCHING PATTERN "*.h"
+-    )
+-  endforeach()
++add_library(fizz_test_support
++crypto/aead/test/TestUtil.cpp
++crypto/test/TestUtil.cpp
++${FIZZ_TEST_HEADERS})
++
++target_link_libraries(fizz_test_support
++PUBLIC
++fizz
++)
++
++# export fizz headers and targets for unit tests utils
++# since other projects such as mvfst and proxygen use them
++install(
++TARGETS fizz_test_support
++EXPORT fizz-exports
++ARCHIVE DESTINATION ${FIZZ_TEST_INSTALL_PREFIX}/lib
++LIBRARY DESTINATION ${FIZZ_TEST_INSTALL_PREFIX}/lib
++)
++
++foreach(dir ${FIZZ_TEST_HEADER_DIRS})
++get_filename_component(PARENT_DIR "/${dir}" DIRECTORY)
++install(
++DIRECTORY ${dir}
++DESTINATION "${FIZZ_TEST_INSTALL_PREFIX}/include/fizz${PARENT_DIR}"
++FILES_MATCHING PATTERN "*.h"
++)
++endforeach()
++
++if(BUILD_TESTS)
++  enable_testing()
+
+   macro(add_gtest test_source test_name)
+     add_executable(${test_name} ${test_source} test/CMakeTestMain.cpp)
+@@ -440,7 +441,7 @@ if(BUILD_TESTS)
+   add_gtest(test/HandshakeTest.cpp HandshakeTest)
+ endif()
+
+-option(BUILD_EXAMPLES "BUILD_EXAMPLES" ON)
++option(BUILD_EXAMPLES "BUILD_EXAMPLES" OFF)
+
+ if(BUILD_EXAMPLES)
+   add_executable(BogoShim test/BogoShim.cpp)
+diff --git a/fizz/cmake/CheckAtomic.cmake b/fizz/cmake/CheckAtomic.cmake
+index b0cadee..2abee5a 100644
+--- a/fizz/cmake/CheckAtomic.cmake
++++ b/fizz/cmake/CheckAtomic.cmake
+@@ -39,55 +39,109 @@
+ # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE
+ # SOFTWARE.
+
+-include(CheckCXXSourceCompiles)
++# atomic builtins are required for threading support.
++
++INCLUDE(CheckCXXSourceCompiles)
++INCLUDE(CheckLibraryExists)
+
+ # Sometimes linking against libatomic is required for atomic ops, if
+ # the platform doesn't support lock-free atomics.
+
+ function(check_working_cxx_atomics varname)
+   set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+-  get_directory_property(compile_options COMPILE_OPTIONS)
+-  set(CMAKE_REQUIRED_FLAGS ${compile_options})
++  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++11")
+   CHECK_CXX_SOURCE_COMPILES("
+ #include <atomic>
++std::atomic<int> x;
+ int main() {
+-  struct Test { int val; };
+-  std::atomic<Test> s;
+-  s.is_lock_free();
+-}" ${varname})
++  return x;
++}
++" ${varname})
+   set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
+ endfunction(check_working_cxx_atomics)
+
++function(check_working_cxx_atomics64 varname)
++  set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
++  set(CMAKE_REQUIRED_FLAGS "-std=c++11 ${CMAKE_REQUIRED_FLAGS}")
++  CHECK_CXX_SOURCE_COMPILES("
++#include <atomic>
++#include <cstdint>
++std::atomic<uint64_t> x (0);
++int main() {
++  uint64_t i = x.load(std::memory_order_relaxed);
++  return 0;
++}
++" ${varname})
++  set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
++endfunction(check_working_cxx_atomics64)
+
+-if(NOT DEFINED PROXYGEN_COMPILER_IS_GCC_COMPATIBLE)
+-  if(CMAKE_COMPILER_IS_GNUCXX)
+-    set(PROXYGEN_COMPILER_IS_GCC_COMPATIBLE ON)
+-  elseif(MSVC)
+-    set(PROXYGEN_COMPILER_IS_GCC_COMPATIBLE OFF)
+-  elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
+-    set(PROXYGEN_COMPILER_IS_GCC_COMPATIBLE ON)
+-  elseif("${CMAKE_CXX_COMPILER_ID}" MATCHES "Intel")
+-    set(PROXYGEN_COMPILER_IS_GCC_COMPATIBLE ON)
+-  endif()
+-endif()
+
+ # This isn't necessary on MSVC, so avoid command-line switch annoyance
+ # by only running on GCC-like hosts.
+-if(PROXYGEN_COMPILER_IS_GCC_COMPATIBLE)
++if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
+   # First check if atomics work without the library.
+   check_working_cxx_atomics(HAVE_CXX_ATOMICS_WITHOUT_LIB)
+   # If not, check if the library exists, and atomics work with it.
+   if(NOT HAVE_CXX_ATOMICS_WITHOUT_LIB)
+-    check_library_exists(atomic __atomic_is_lock_free "" HAVE_LIBATOMIC)
+-    if(HAVE_LIBATOMIC)
++    check_library_exists(atomic __atomic_fetch_add_4 "" HAVE_LIBATOMIC)
++    if( HAVE_LIBATOMIC )
+       list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
+       check_working_cxx_atomics(HAVE_CXX_ATOMICS_WITH_LIB)
+       if (NOT HAVE_CXX_ATOMICS_WITH_LIB)
+-	message(FATAL_ERROR "Host compiler must support std::atomic!")
++    message(FATAL_ERROR "Host compiler must support std::atomic!")
+       endif()
+-      list(APPEND CMAKE_CXX_STANDARD_LIBRARIES -latomic)
+     else()
+       message(FATAL_ERROR "Host compiler appears to require libatomic, but cannot find it.")
+     endif()
+   endif()
+ endif()
++
++# Check for 64 bit atomic operations.
++if(MSVC)
++  set(HAVE_CXX_ATOMICS64_WITHOUT_LIB True)
++else()
++  check_working_cxx_atomics64(HAVE_CXX_ATOMICS64_WITHOUT_LIB)
++endif()
++
++# If not, check if the library exists, and atomics work with it.
++if(NOT HAVE_CXX_ATOMICS64_WITHOUT_LIB)
++  check_library_exists(atomic __atomic_load_8 "" HAVE_CXX_LIBATOMICS64)
++  if(HAVE_CXX_LIBATOMICS64)
++    list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
++    check_working_cxx_atomics64(HAVE_CXX_ATOMICS64_WITH_LIB)
++    if (NOT HAVE_CXX_ATOMICS64_WITH_LIB)
++      message(FATAL_ERROR "Host compiler must support 64-bit std::atomic!")
++    endif()
++  else()
++    message(FATAL_ERROR "Host compiler appears to require libatomic for 64-bit operations, but cannot find it.")
++  endif()
++endif()
++
++## TODO: This define is only used for the legacy atomic operations in
++## llvm's Atomic.h, which should be replaced.  Other code simply
++## assumes C++11 <atomic> works.
++CHECK_CXX_SOURCE_COMPILES("
++#ifdef _MSC_VER
++#include <windows.h>
++#endif
++int main() {
++#ifdef _MSC_VER
++        volatile LONG val = 1;
++        MemoryBarrier();
++        InterlockedCompareExchange(&val, 0, 1);
++        InterlockedIncrement(&val);
++        InterlockedDecrement(&val);
++#else
++        volatile unsigned long val = 1;
++        __sync_synchronize();
++        __sync_val_compare_and_swap(&val, 1, 0);
++        __sync_add_and_fetch(&val, 1);
++        __sync_sub_and_fetch(&val, 1);
++#endif
++        return 0;
++      }
++" LLVM_HAS_ATOMICS)
++
++if( NOT LLVM_HAS_ATOMICS )
++  message(STATUS "Warning: LLVM will be built thread-unsafe because atomic builtins are missing")
++endif()
diff --git a/projects/proxygen/folly_patch.txt b/projects/proxygen/folly_patch.txt
@@ -0,0 +1,49 @@
+diff --git a/CMake/FollyCompilerUnix.cmake b/CMake/FollyCompilerUnix.cmake
+index 9c76fdc6..186f3f30 100644
+--- a/CMake/FollyCompilerUnix.cmake
++++ b/CMake/FollyCompilerUnix.cmake
+@@ -19,7 +19,7 @@ set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} ${CMAKE_CXX_FLAGS_COMMON}")
+ set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} ${CMAKE_CXX_FLAGS_COMMON} -O3")
+
+ # Note that CMAKE_REQUIRED_FLAGS must be a string, not a list
+-set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=${CXX_STD}")
++#set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=${CXX_STD}")
+ list(APPEND CMAKE_REQUIRED_DEFINITIONS "-D_GNU_SOURCE")
+ function(apply_folly_compile_options_to_target THETARGET)
+   target_compile_definitions(${THETARGET}
+diff --git a/CMake/folly-deps.cmake b/CMake/folly-deps.cmake
+index 0fb8a90a..9c4599b2 100644
+--- a/CMake/folly-deps.cmake
++++ b/CMake/folly-deps.cmake
+@@ -117,7 +117,7 @@ CHECK_INCLUDE_FILE_CXX(elf.h FOLLY_HAVE_ELF_H)
+ find_library(UNWIND_LIBRARIES NAMES unwind)
+ if (UNWIND_LIBRARIES)
+   list(APPEND FOLLY_LINK_LIBRARIES ${UNWIND_LIBRARIES})
+-  list(APPEND CMAKE_REQUIRED_LIBRARIES ${UNWIND_LIBRARIES})
++  list(APPEND CMAKE_REQUIRED_LIBRARIES ${UNWIND_LIBRARIES} ${LIBLZMA_LIBRARIES})
+ endif()
+ check_function_exists(backtrace FOLLY_HAVE_BACKTRACE)
+ if (FOLLY_HAVE_ELF_H AND FOLLY_HAVE_BACKTRACE AND LIBDWARF_FOUND)
+@@ -155,6 +155,7 @@ if(NOT FOLLY_CPP_ATOMIC_BUILTIN)
+   endif()
+ endif()
+
++
+ option(
+   FOLLY_LIBRARY_SANITIZE_ADDRESS
+   "Build folly with Address Sanitizer enabled."
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 6d785431..38228903 100755
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -13,6 +13,10 @@ if(POLICY CMP0075)
+   cmake_policy(SET CMP0075 NEW)
+ endif()
+
++if(POLICY CMP0067)
++  cmake_policy(SET CMP0067 NEW)
++endif()
++
+ # includes
+ set(CMAKE_MODULE_PATH
+   "${CMAKE_CURRENT_SOURCE_DIR}/CMake"