[ubsan] Implement __sanitizer_print_stack_trace for standalone UBSan runtime.

[Dor1s]

Summary

Landed by @glider (thanks!) as git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@302218 91177308-0d34-0410-b5e6-96231b3b80d8

[glider]

LGTM

[Dor1s]

Thanks Alexander!

FTR, the reason why I'm adding this change: https://github.com/google/oss-fuzz/issues/552

I tested this change manually and it works as expected.

Regarding llvm tests, I tried check-ubsan and check-sanitizer, both of them are not executing print-stack-trace test for UBSan. However, check-sanitizer executes print-stack-trace test for other sanitizers, as Alexander mentioned.

I'll try to enable UBSan to llvm/projects/compiler-rt/test/sanitizer_common/lit.common.cfg, but don't believe that it'll work as is... I'll post an update soon.

Another options are:

1. duplicate projects/compiler-rt/test/sanitizer_common/TestCases/print-stack-trace.cc into UBSan-specific tests
2. commit this change as-is

[Dor1s]

No luck with enabling sanitizer-common tests for UBSan Standalone so far.

[Dor1s]

Adding list(APPEND SUPPORTED_TOOLS ubsan) into compiler-rt/test/sanitizer_common/CMakeLists.txt works, but lots of tests are failing as I expected :(

[vsk]

lib/ubsan/ubsan_diag_standalone.cc

27

I think this requests the slow unwinder, which isn't available on Darwin. Maybe it would be better to use the fast unwinder? E.g: https://reviews.llvm.org/D32517

[eugenis]

There should be a test for this. It would catch this potential Mac problem, too.

lib/ubsan/ubsan_diag_standalone.cc

25

This may break on Mac, where the slow unwinder is disabled. See the code in MaybePrintStackTrace() in ubsan_diag.cc.

[Dor1s]

Thanks for taking a look ! I added fast unwind call. It's still unclear for me how to add a test properly. If I add a separate UBSan-only test for __sanitizer_print_stack_trace, it doesn't work correctly as every UBSan test is being invoked in 4 configurations:

• Standalone
• ASan
• MSan
• TSan

and configurations other than 'Standalone' are using their __sanitizer_print_stack_trace implementations, so the test fails.

If I add UBSan to invoke sanitizer_common test suite, it fails too much, as nobody expected those tests to be passed.

I'd appreciate if you can share any hints what to do :)

[Dor1s]

Ok, looks like I did it. The added test passes with all the configurations.

[eugenis]

lib/ubsan/ubsan_diag_standalone.cc

27

See https://reviews.llvm.org/D32517, this code needs to get stack limits for the fast unwinder, and also it should respect fast_unwind_on_fatal as the other sanitizers do.

Basically, the same as D32517 but without the check for flags()->print_stacktrace.

Wait until that lands and reuse the code?

test/ubsan/TestCases/Common/print-stack-trace.cc

1 ↗

(On Diff #97079)

test with the fast unwinder, too

14 ↗

(On Diff #97079)

AFAIR we usually do it like this:
FooBarBaz{{.*}}print-stack-trace.cc

No space and no argument list because symbolization works slightly differently on some platforms.

[Dor1s]

Thanks Evgenii for the review!

lib/ubsan/ubsan_diag_standalone.cc

27

Thanks Evgenii, that's a great suggestion! Done.

[Dor1s]

Addressed the comments, re-used new implementation from https://reviews.llvm.org/D32517.

[Dor1s]

Almost done. Still cannot make the test happy on Mac, but now only TSan config is failing:

Failing Tests (2):
    UBSan-TSan-x86_64 :: TestCases/Common/print-stack-trace.cc
    UBSan-TSan-x86_64h :: TestCases/Common/print-stack-trace.cc


  Expected Passes    : 279
  Expected Failures  : 10
  Unsupported Tests  : 13
  Unexpected Failures: 2

Because:

$ <..>/work/llvm/projects/compiler-rt/test/ubsan/ThreadSanitizer-x86_64/TestCases/Common/Output/print-stack-trace.cc.tmp
    #0 __sanitizer_print_stack_trace tsan_rtl_report.cc:727 (libclang_rt.tsan_osx_dynamic.dylib:x86_64h+0x5cefb)

It uses TSan's implementation, not UBSan. I'll compare this behavior with Linux to find the root cause.

[Dor1s]

As per summary of https://reviews.llvm.org/D32517, the slow unwinder is not supported on Darwin, but __sanitizer_print_stack_trace in Darwin is using slow unwind only (https://github.com/llvm-mirror/compiler-rt/blob/master/lib/tsan/rtl/tsan_rtl_report.cc#L726). This is why my test is failing with TSan.

I'll play with TSan as well.

[Dor1s]

This is final version for now, please take a look.

Regarding TSan, I'll upload a patch to https://reviews.llvm.org/D32806, but it needs more thoughts probably.

Huge thanks to Alexander @glider for helping me with debugging and other issues!

[Dor1s]

All the comments have been addressed. Can we land this?

lib/ubsan/CMakeLists.txt

 # Build for the undefined behavior sanitizer runtime support library.
 
 set(UBSAN_SOURCES
   ubsan_diag.cc
   ubsan_init.cc
   ubsan_flags.cc
   ubsan_handlers.cc
   ubsan_value.cc
   )
 
 set(UBSAN_STANDALONE_SOURCES
+  ubsan_diag_standalone.cc
   ubsan_init_standalone.cc
   )
 
 set(UBSAN_CXXABI_SOURCES
   ubsan_handlers_cxx.cc
   ubsan_type_hash.cc
   ubsan_type_hash_itanium.cc
   ubsan_type_hash_win.cc

lib/ubsan/ubsan_diag_standalone.cc

+//===-- ubsan_diag_standalone.cc ------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Diagnostic reporting for the standalone UBSan runtime.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ubsan_platform.h"
+#if CAN_SANITIZE_UB
+#include "ubsan_diag.h"
+
+using namespace __ubsan;
+
+extern "C" {
+SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_print_stack_trace() {
+  GET_REPORT_OPTIONS(false);
+  BufferedStackTrace stack;
+  stack.Unwind(kStackTraceMax, Opts.pc, Opts.bp, 0, 0, 0, false);
+  stack.Print();
+}
+} // extern "C"
+
+#endif  // CAN_SANITIZE_UB