[asan] Split SIGSEGV/SIGBUS handling so we can handle only one of them and not the other.

[filcab]

Summary

This is useful in some platforms where one of these signals is special.
I'm not sure how to write cross-platform tests for this, though.

[kcc]

what are those platforms and can we have at the very least tests for those platforms?
(Also, would be nice to have tests for linux/mac, but frankly I don't remember how to cause a SIGBUS on linux)

[filcab]

Added a test for POSIX systems.

[filcab]

Put the test in the correct directory.

[kcc]

test/asan/TestCases/Posix/asan-sigbus.cpp

4

don't compile twice.
what's handle_bug?

[filcab]

Updating and fixing test

[filcab]

In D30783#697231, @kcc wrote:

what are those platforms and can we have at the very least tests for those platforms?
(Also, would be nice to have tests for linux/mac, but frankly I don't remember how to cause a SIGBUS on linux)

Hi Kostya,

The PS4 needs to handle those signals differently. As of right now, we can't upload the modifications to make ASan work on it, though. I doubt it would be useful to upstream a test with REQUIRES: ps4, though.

test/asan/TestCases/Posix/asan-sigbus.cpp

4

A bug in the command line. Updating.

[kcc]

LGTM
Please watch the bots, the change is a bit risky

lib/asan/tests/asan_test.cc

 # if defined(__powerpc64__)
   char *addr = (char*)0x024000800000;
 # elif defined(__s390x__)
   char *addr = (char*)0x11000000000000;
 # else
   char *addr = (char*)0x0000100000080000;
 # endif
 #endif
-  EXPECT_DEATH(*addr = 1, "AddressSanitizer: SEGV on unknown");
+  EXPECT_DEATH(*addr = 1, "AddressSanitizer: BUS on unknown");
 }
 #endif  // ASAN_NEEDS_SEGV
 
 extern "C" {
 NOINLINE static void UseThenFreeThenUse() {
   char *x = Ident((char*)malloc(8));
   *x = 1;
   free_aaa(x);

lib/sanitizer_common/sanitizer_flags.inc

 COMMON_FLAG(bool, print_summary, true,
             "If false, disable printing error summaries in addition to error "
             "reports.")
 COMMON_FLAG(int, print_module_map, 0,
             "OS X only. 0 = don't print, 1 = print only once before process "
             "exits, 2 = print after each report.")
 COMMON_FLAG(bool, check_printf, true, "Check printf arguments.")
 COMMON_FLAG(bool, handle_segv, true,
-            "If set, registers the tool's custom SIGSEGV/SIGBUS handler.")
+            "If set, registers the tool's custom SIGSEGV handler.")
+COMMON_FLAG(bool, handle_sigbus, true,
+            "If set, registers the tool's custom SIGBUS handler.")
 COMMON_FLAG(bool, handle_abort, false,
             "If set, registers the tool's custom SIGABRT handler.")
 COMMON_FLAG(bool, handle_sigill, false,
             "If set, registers the tool's custom SIGILL handler.")
 COMMON_FLAG(bool, handle_sigfpe, true,
             "If set, registers the tool's custom SIGFPE handler.")
 COMMON_FLAG(bool, allow_user_segv_handler, false,
             "If set, allows user to register a SEGV handler even if the tool "

lib/sanitizer_common/sanitizer_linux.cc

 
 bool IsHandledDeadlySignal(int signum) {
   if (common_flags()->handle_abort && signum == SIGABRT)
     return true;
   if (common_flags()->handle_sigill && signum == SIGILL)
     return true;
   if (common_flags()->handle_sigfpe && signum == SIGFPE)
     return true;
-  return (signum == SIGSEGV || signum == SIGBUS) && common_flags()->handle_segv;
+  if (common_flags()->handle_segv && signum == SIGSEGV)
+    return true;
+  return common_flags()->handle_sigbus && signum == SIGBUS;
 }
 
 #if !SANITIZER_GO
 void *internal_start_thread(void(*func)(void *arg), void *arg) {
   // Start the thread with signals blocked, otherwise it can steal user signals.
   __sanitizer_sigset_t set, old;
   internal_sigfillset(&set);
 #if SANITIZER_LINUX && !SANITIZER_ANDROID

lib/sanitizer_common/sanitizer_mac.cc

if ((SANITIZER_WATCHOS || SANITIZER_TVOS) && !(SANITIZER_IOSSIM))
     // Handling fatal signals on watchOS and tvOS devices is disallowed.
     return false;
   if (common_flags()->handle_abort && signum == SIGABRT)
     return true;
   if (common_flags()->handle_sigill && signum == SIGILL)
     return true;
   if (common_flags()->handle_sigfpe && signum == SIGFPE)
     return true;
-  return (signum == SIGSEGV || signum == SIGBUS) && common_flags()->handle_segv;
+  if (common_flags()->handle_segv && signum == SIGSEGV)
+    return true;
+  return common_flags()->handle_sigbus && signum == SIGBUS;
 }
 
 MacosVersion cached_macos_version = MACOS_VERSION_UNINITIALIZED;
 
 MacosVersion GetMacosVersionInternal() {
   int mib[2] = { CTL_KERN, KERN_OSRELEASE };
   char version[100];
   uptr len = 0, maxlen = sizeof(version) / sizeof(version[0]);

lib/sanitizer_common/sanitizer_posix.cc

 const char *DescribeSignalOrException(int signo) {
   switch (signo) {
     case SIGFPE:
       return "FPE";
     case SIGILL:
       return "ILL";
     case SIGABRT:
       return "ABRT";
-    default:
+    case SIGSEGV:
       return "SEGV";
+    case SIGBUS:
+      return "BUS";
   }
   return "UNKNOWN SIGNAL";
 }
 
 } // namespace __sanitizer
 
 #endif // SANITIZER_POSIX

test/asan/TestCases/Posix/asan-sigbus.cpp

+// Check handle_bus flag
+// Defaults to true
+// RUN: %clangxx_asan -std=c++11 %s -o %t && not %run %t %T/file 2>&1 | FileCheck %s -check-prefix=CHECK -check-prefix=CHECK-BUS
+// RUN: %clangxx_asan -std=c++11 %s -o %t && %env_asan_opts=handle_bug=false not %run %t %T/file 2>&1 | FileCheck %s
+
+#include <assert.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+char array[4096];
+int main(int argc, char **argv) {
+  assert(argc > 1);
+  int fd = open(argv[1], O_RDWR | O_CREAT, 0700);
+  if (fd < 0) {
+    perror("open");
+    exit(1);
+  }
+  assert(write(fd, array, sizeof(array)) == sizeof(array));
+
+  // Write some zeroes to the file, then mmap it while it has a 4KiB size
+  char *addr = (char *)mmap(nullptr, sizeof(array), PROT_READ,
+                            MAP_FILE | MAP_SHARED, fd, 0);
+  if (addr == MAP_FAILED) {
+    perror("mmap");
+    exit(1);
+  }
+
+  // Truncate the file so our memory isn't valid any more
+  assert(ftruncate(fd, 0) == 0);
+
+  // Try to access the memory
+  return addr[42];
+  // CHECK: DEADLYSIGNAL
+  // CHECK-BUS: ERROR: AddressSanitizer: BUS
+}