[Sanitizer] checks ASLR on FreeBSD

[devnexen]

Summary

• Especially MemorySanitizer fails if those sysctl configs are enabled.

[dim]

LGTM. Maybe nice to merge it to 9.0 after a day or two.

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

2027 ↗

(On Diff #216586)

Note that the aslr.pie_enable sysctl is specifically for PIE executables, so maybe mention that? (This is just a nit.)

[devnexen]

In D66582#1641454, @dim wrote:

LGTM. Maybe nice to merge it to 9.0 after a day or two.

Done now https://github.com/llvm/llvm-project/commit/a3a8bf9beb52348f5286663c772d51ae8fb39357

compiler-rt/trunk/lib/asan/asan_rtl.cpp

 
 static void AsanInitInternal() {
   if (LIKELY(asan_inited)) return;
   SanitizerToolName = "AddressSanitizer";
   CHECK(!asan_init_is_running && "ASan init calls itself!");
   asan_init_is_running = true;
 
   CacheBinaryName();
-  CheckASLR();
 
   // Initialize flags. This must be done early, because most of the
   // initialization steps look at flags().
   InitializeFlags();
 
   // Stop performing init at this point if we are being loaded via
   // dlopen() and the platform supports it.
   if (SANITIZER_SUPPORTS_INIT_FOR_DLOPEN && UNLIKELY(HandleDlopenInit())) {
static void AsanInitInternal() {
   // Re-exec ourselves if we need to set additional env or command line args.
   MaybeReexec();
 
   // Setup internal allocator callback.
   SetLowLevelAllocateMinAlignment(SHADOW_GRANULARITY);
   SetLowLevelAllocateCallback(OnLowLevelAllocate);
 
   InitializeAsanInterceptors();
+  CheckASLR();
 
   // Enable system log ("adb logcat") on Android.
   // Doing this before interceptors are initialized crashes in:
   // AsanInitInternal -> android_log_write -> __interceptor_strcmp
   AndroidLogInit();
 
   ReplaceSystemMalloc();
 

compiler-rt/trunk/lib/msan/msan.cpp

void __msan_init() {
   CHECK(!msan_init_is_running);
   if (msan_inited) return;
   msan_init_is_running = 1;
   SanitizerToolName = "MemorySanitizer";
 
   AvoidCVE_2016_2143();
 
   CacheBinaryName();
-  CheckASLR();
   InitializeFlags();
 
   // Install tool-specific callbacks in sanitizer_common.
   SetCheckFailedCallback(MsanCheckFailed);
 
   __sanitizer_set_report_path(common_flags()->log_path);
 
   InitializeInterceptors();
+  CheckASLR();
   InitTlsSize();
   InstallDeadlySignalHandlers(MsanOnDeadlySignal);
   InstallAtExitHandler(); // Needs __cxa_atexit interceptor.
 
   DisableCoreDumperIfNecessary();
   if (StackSizeIsUnlimited()) {
     VPrintf(1, "Unlimited stack, doing reexec\n");
     // A reasonably large stack size. It is bigger than the usual 8Mb, because,

compiler-rt/trunk/lib/sanitizer_common/sanitizer_linux.cpp

#elif SANITIZER_PPC64V2
   if (old_personality != -1 && (old_personality & ADDR_NO_RANDOMIZE) == 0) {
     VReport(1, "WARNING: Program is being run with address space layout "
                "randomization (ASLR) enabled which prevents the thread and "
                "memory sanitizers from working on powerpc64le.\n"
                "ASLR will be disabled and the program re-executed.\n");
     CHECK_NE(personality(old_personality | ADDR_NO_RANDOMIZE), -1);
     ReExec();
   }
+#elif SANITIZER_FREEBSD
+  int aslr_pie;
+  uptr len = sizeof(aslr_pie);
+#if SANITIZER_WORDSIZE == 64
+  if (UNLIKELY(internal_sysctlbyname("kern.elf64.aslr.pie_enable",
+      &aslr_pie, &len, NULL, 0) == -1)) {
+    // We're making things less 'dramatic' here since
+    // the OID is not necessarily guaranteed to be here
+    // just yet regarding FreeBSD release
+    return;
+  }
+
+  if (aslr_pie > 0) {
+    Printf("This sanitizer is not compatible with enabled ASLR and binaries compiled with PIE\n");
+    Die();
+  }
+#endif
+  // there might be 32 bits compat for 64 bits
+  if (UNLIKELY(internal_sysctlbyname("kern.elf32.aslr.pie_enable",
+      &aslr_pie, &len, NULL, 0) == -1)) {
+    return;
+  }
+
+  if (aslr_pie > 0) {
+    Printf("This sanitizer is not compatible with enabled ASLR and binaries compiled with PIE\n");
+    Die();
+  }
 #else
   // Do nothing
 #endif
 }
 
 void CheckMPROTECT() {
 #if SANITIZER_NETBSD
   int mib[3];