[cfi] Lazy initialization of CFI interceptors
Summary:
Interceptors initialization may need to allocate memory. So if we initialize too
early we can crash in non initialized allocator.
Reviewers: pcc, eugenis
Subscribers: llvm-commits
@@ -379,6 +379,8 @@ __cfi_slowpath_diag(u64 CallSiteTypeId, void *Ptr, void *DiagData) {
}
#endif
+static void EnsureInterceptorsInitialized();
+
// Setup shadow for dlopen()ed libraries.
// The actual shadow setup happens after dlopen() returns, which means that
// a library can not be a target of any CFI checks while its constructors are
@@ -388,6 +390,7 @@ __cfi_slowpath_diag(u64 CallSiteTypeId, void *Ptr, void *DiagData) {
// We could insert a high-priority constructor into the library, but that would
// not help with the uninstrumented libraries.
INTERCEPTOR(void*, dlopen, const char *filename, int flag) {
+ EnsureInterceptorsInitialized();
EnterLoader();
void *handle = REAL(dlopen)(filename, flag);
ExitLoader();
@@ -395,12 +398,27 @@ INTERCEPTOR(void*, dlopen, const char *filename, int flag) {
}
INTERCEPTOR(int, dlclose, void *handle) {
+ EnsureInterceptorsInitialized();
EnterLoader();
int res = REAL(dlclose)(handle);
ExitLoader();
return res;
}
+static BlockingMutex interceptor_init_lock(LINKER_INITIALIZED);
+static bool interceptors_inited = false;
+
+static void EnsureInterceptorsInitialized() {
+ BlockingMutexLock lock(&interceptor_init_lock);
+ if (interceptors_inited)
+ return;
+
+ INTERCEPT_FUNCTION(dlopen);
+ INTERCEPT_FUNCTION(dlclose);
+
+ interceptors_inited = true;
+}
+
extern "C" SANITIZER_INTERFACE_ATTRIBUTE
#if !SANITIZER_CAN_USE_PREINIT_ARRAY
// On ELF platforms, the constructor is invoked using .preinit_array (see below)
@@ -411,9 +429,6 @@ void __cfi_init() {
InitializeFlags();
InitShadow();
- INTERCEPT_FUNCTION(dlopen);
- INTERCEPT_FUNCTION(dlclose);
-
#ifdef CFI_ENABLE_DIAG
__ubsan::InitAsPlugin();
#endif
