[compiler-rt][builtins] Add compiler flags to catch potential errors

that can lead to security vulnerabilities

Also, fix a few places that were causing -Wshadow and
-Wformat-nonliteral warnings to be emitted.

This reapplies the patch that was reverted in caaafe4ae250 because it
broke Fuchsia builders.

I reverted the changes I made to InstrProfData.inc and instead renamed
the variables in InstrProfilingWriter.c. Also fixed a bug in function
add_security_warnings that was causing it to pass -Wformat-nonliteral
when the compiler doesn't support it.

compiler-rt/cmake/Modules/CompilerRTDarwinUtils.cmake

@@ -413,6 +413,12 @@ macro(darwin_add_builtin_libraries)
                       ../profile/InstrProfilingInternal.c
                       ../profile/InstrProfilingVersionVar.c)
   foreach (os ${ARGN})
+    set(macosx_sdk_version 99999)
+    if ("${os}" STREQUAL "osx")
+      find_darwin_sdk_version(macosx_sdk_version "macosx")
+    endif()
+    add_security_warnings(CFLAGS ${macosx_sdk_version})
+
     list_intersect(DARWIN_BUILTIN_ARCHS DARWIN_${os}_BUILTIN_ARCHS BUILTIN_SUPPORTED_ARCH)
 
     if((arm64 IN_LIST DARWIN_BUILTIN_ARCHS OR arm64e IN_LIST DARWIN_BUILTIN_ARCHS) AND NOT TARGET lse_builtin_symlinks)

compiler-rt/cmake/Modules/CompilerRTUtils.cmake

@@ -593,3 +593,32 @@ function(add_compiler_rt_install_targets name)
     endif()
   endif()
 endfunction()
+
+# Add warnings to catch potential errors that can lead to security
+# vulnerabilities.
+function(add_security_warnings out_flags macosx_sdk_version)
+  set(flags "${${out_flags}}")
+
+  append_list_if(COMPILER_RT_HAS_ARRAY_BOUNDS_FLAG -Werror=array-bounds flags)
+  append_list_if(COMPILER_RT_HAS_UNINITIALIZED_FLAG -Werror=uninitialized flags)
+  append_list_if(COMPILER_RT_HAS_SHADOW_FLAG -Werror=shadow flags)
+  append_list_if(COMPILER_RT_HAS_EMPTY_BODY_FLAG -Werror=empty-body flags)
+  append_list_if(COMPILER_RT_HAS_SIZEOF_POINTER_MEMACCESS_FLAG -Werror=sizeof-pointer-memaccess flags)
+  append_list_if(COMPILER_RT_HAS_SIZEOF_ARRAY_ARGUMENT_FLAG -Werror=sizeof-array-argument flags)
+  append_list_if(COMPILER_RT_HAS_MEMSET_TRANSPOSED_ARGS_FLAG -Werror=memset-transposed-args flags)
+  append_list_if(COMPILER_RT_HAS_BUILTIN_MEMCPY_CHK_SIZE_FLAG -Werror=builtin-memcpy-chk-size flags)
+  append_list_if(COMPILER_RT_HAS_ARRAY_BOUNDS_POINTER_ARITHMETIC_FLAG -Werror=array-bounds-pointer-arithmetic flags)
+  append_list_if(COMPILER_RT_HAS_RETURN_STACK_ADDRESS_FLAG -Werror=return-stack-address flags)
+  append_list_if(COMPILER_RT_HAS_SIZEOF_ARRAY_DECAY_FLAG -Werror=sizeof-array-decay flags)
+  append_list_if(COMPILER_RT_HAS_FORMAT_INSUFFICIENT_ARGS_FLAG -Werror=format-insufficient-args flags)
+  append_list_if(COMPILER_RT_HAS_BUILTIN_FORMAL_SECURITY_FLAG -Werror=format-security flags)
+
+  # Add -Wformat-nonliteral only if we can avoid adding the definition of
+  # eprintf. On Apple platforms, eprintf is needed only on macosx and only if
+  # its version is older than 10.7.
+  if ("${macosx_sdk_version}" VERSION_GREATER_EQUAL 10.7)
+    list(APPEND flags -Werror=format-nonliteral -DDONT_DEFINE_EPRINTF)
+  endif()
+
+  set(${out_flags} "${flags}" PARENT_SCOPE)
+endfunction()

compiler-rt/cmake/config-ix.cmake

@@ -137,6 +137,20 @@ check_cxx_compiler_flag(/wd4391 COMPILER_RT_HAS_WD4391_FLAG)
 check_cxx_compiler_flag(/wd4722 COMPILER_RT_HAS_WD4722_FLAG)
 check_cxx_compiler_flag(/wd4800 COMPILER_RT_HAS_WD4800_FLAG)
 
+check_cxx_compiler_flag(-Warray-bounds COMPILER_RT_HAS_ARRAY_BOUNDS_FLAG)
+check_cxx_compiler_flag(-Wuninitialized COMPILER_RT_HAS_UNINITIALIZED_FLAG)
+check_cxx_compiler_flag(-Wshadow COMPILER_RT_HAS_SHADOW_FLAG)
+check_cxx_compiler_flag(-Wempty-body COMPILER_RT_HAS_EMPTY_BODY_FLAG)
+check_cxx_compiler_flag(-Wsizeof-pointer-memaccess COMPILER_RT_HAS_SIZEOF_POINTER_MEMACCESS_FLAG)
+check_cxx_compiler_flag(-Wsizeof-array-argument COMPILER_RT_HAS_SIZEOF_ARRAY_ARGUMENT_FLAG)
+check_cxx_compiler_flag(-Wmemset-transposed-args COMPILER_RT_HAS_MEMSET_TRANSPOSED_ARGS_FLAG)
+check_cxx_compiler_flag(-Wbuiltin-memcpy-chk-size COMPILER_RT_HAS_BUILTIN_MEMCPY_CHK_SIZE_FLAG)
+check_cxx_compiler_flag(-Warray-bounds-pointer-arithmetic COMPILER_RT_HAS_ARRAY_BOUNDS_POINTER_ARITHMETIC_FLAG)
+check_cxx_compiler_flag(-Wreturn-stack-address COMPILER_RT_HAS_RETURN_STACK_ADDRESS_FLAG)
+check_cxx_compiler_flag(-Wsizeof-array-decay COMPILER_RT_HAS_SIZEOF_ARRAY_DECAY_FLAG)
+check_cxx_compiler_flag(-Wformat-insufficient-args COMPILER_RT_HAS_FORMAT_INSUFFICIENT_ARGS_FLAG)
+check_cxx_compiler_flag(-Wformat-security COMPILER_RT_HAS_BUILTIN_FORMAL_SECURITY_FLAG)
+
 # Symbols.
 check_symbol_exists(__func__ "" COMPILER_RT_HAS_FUNC_SYMBOL)
 

compiler-rt/lib/builtins/CMakeLists.txt

@@ -699,6 +699,7 @@ if (APPLE)
   darwin_add_builtin_libraries(${BUILTIN_SUPPORTED_OS})
 else ()
   set(BUILTIN_CFLAGS "")
+  add_security_warnings(BUILTIN_CFLAGS 0)
 
   if (COMPILER_RT_HAS_FCF_PROTECTION_FLAG)
     append_list_if(COMPILER_RT_ENABLE_CET -fcf-protection=full BUILTIN_CFLAGS)

compiler-rt/lib/builtins/eprintf.c

@@ -15,6 +15,7 @@
 //
 // It should never be exported from a dylib, so it is marked
 // visibility hidden.
+#ifndef DONT_DEFINE_EPRINTF
 #ifndef _WIN32
 __attribute__((visibility("hidden")))
 #endif
@@ -25,3 +26,4 @@ __eprintf(const char *format, const char *assertion_expression,
   fflush(stderr);
   compilerrt_abort();
 }
+#endif

compiler-rt/lib/profile/InstrProfiling.c

@@ -64,11 +64,11 @@ COMPILER_RT_VISIBILITY void __llvm_profile_reset_counters(void) {
       CurrentVSiteCount += DI->NumValueSites[VKI];
 
     for (i = 0; i < CurrentVSiteCount; ++i) {
-      ValueProfNode *CurrentVNode = ValueCounters[i];
+      ValueProfNode *CurrVNode = ValueCounters[i];
 
-      while (CurrentVNode) {
-        CurrentVNode->Count = 0;
-        CurrentVNode = CurrentVNode->Next;
+      while (CurrVNode) {
+        CurrVNode->Count = 0;
+        CurrVNode = CurrVNode->Next;
       }
     }
   }

compiler-rt/lib/profile/InstrProfilingWriter.c

@@ -263,11 +263,11 @@ lprofWriteDataImpl(ProfDataWriter *Writer, const __llvm_profile_data *DataBegin,
       (__llvm_profile_get_version() & VARIANT_MASK_DBG_CORRELATE) != 0ULL;
 
   /* Calculate size of sections. */
-  const uint64_t DataSize =
+  const uint64_t DataSectionSize =
       DebugInfoCorrelate ? 0 : __llvm_profile_get_data_size(DataBegin, DataEnd);
   const uint64_t NumData =
       DebugInfoCorrelate ? 0 : __llvm_profile_get_num_data(DataBegin, DataEnd);
-  const uint64_t CountersSize =
+  const uint64_t CountersSectionSize =
       __llvm_profile_get_counters_size(CountersBegin, CountersEnd);
   const uint64_t NumCounters =
       __llvm_profile_get_num_counters(CountersBegin, CountersEnd);
@@ -284,8 +284,9 @@ lprofWriteDataImpl(ProfDataWriter *Writer, const __llvm_profile_data *DataBegin,
   uint64_t PaddingBytesBeforeCounters, PaddingBytesAfterCounters,
       PaddingBytesAfterNames;
   __llvm_profile_get_padding_sizes_for_counters(
-      DataSize, CountersSize, NamesSize, &PaddingBytesBeforeCounters,
-      &PaddingBytesAfterCounters, &PaddingBytesAfterNames);
+      DataSectionSize, CountersSectionSize, NamesSize,
+      &PaddingBytesBeforeCounters, &PaddingBytesAfterCounters,
+      &PaddingBytesAfterNames);
 
   {
     // TODO: Unfortunately the header's fields are named DataSize and
@@ -321,9 +322,10 @@ lprofWriteDataImpl(ProfDataWriter *Writer, const __llvm_profile_data *DataBegin,
 
   /* Write the profile data. */
   ProfDataIOVec IOVecData[] = {
-      {DebugInfoCorrelate ? NULL : DataBegin, sizeof(uint8_t), DataSize, 0},
+      {DebugInfoCorrelate ? NULL : DataBegin, sizeof(uint8_t), DataSectionSize,
+       0},
       {NULL, sizeof(uint8_t), PaddingBytesBeforeCounters, 1},
-      {CountersBegin, sizeof(uint8_t), CountersSize, 0},
+      {CountersBegin, sizeof(uint8_t), CountersSectionSize, 0},
       {NULL, sizeof(uint8_t), PaddingBytesAfterCounters, 1},
       {(SkipNameDataWrite || DebugInfoCorrelate) ? NULL : NamesBegin,
        sizeof(uint8_t), NamesSize, 0},