[lldb-dev] [cfe-dev] [5.0.0 Release] Release Candidate 1 tagged

[Dimitry Andric via lldb-dev]

On 31 Jul 2017, at 19:26, Hans Wennborg <hans at chromium.org> wrote:
> 
> On Sat, Jul 29, 2017 at 4:59 AM, Dimitry Andric <dimitry at andric.com> wrote:
>> On 27 Jul 2017, at 00:41, Hans Wennborg via cfe-dev <cfe-dev at lists.llvm.org> wrote:
>>> 
>>> 5.0.0-rc1 has just been tagged.
>>> 
>>> Please build, test and upload binaries to the sftp. Let me know if
>>> there are any issues.
>> 
>> Built and tested rc1.  Test failures on amd64-freebsd10:
>> 
>> FAIL: LLVM-Unit :: ExecutionEngine/Orc/./OrcJITTests/DummyRPC.TestClearHandlers (1346 of 38616)
>> FAIL: AddressSanitizer-Unit :: ./Asan-i386-inline-Test/AddressSanitizer.DoubleFreeTest (2480 of 38616)
>> FAIL: AddressSanitizer-Unit :: ./Asan-i386-inline-Test/AddressSanitizer.ReallocFreedPointerTest (2505 of 38616)
>> FAIL: AddressSanitizer-Unit :: ./Asan-i386-inline-Test/AddressSanitizer.UseThenFreeThenUseTest (2542 of 38616)
>> FAIL: AddressSanitizer-Unit :: ./Asan-i386-inline-Test/AddressSanitizer.WrongFreeTest (2546 of 38616)
...
> Do we know what's up with all of these ASan failures? Is there a bug for it?

I spent a limited amount of debugging on it, but the common problem is that on i386 (aka 32-bit x86) all programs compiled with -fsanitize=address now die with:

==11122==AddressSanitizer CHECK failed: /usr/src/contrib/compiler-rt/lib/asan/asan_poisoning.cc:36 "((AddrIsAlignedByGranularity(addr))) != (0)" (0x0, 0x0)
    #0 0x806f163 in __asan::AsanCheckFailed(char const*, int, char const, unsigned long long, unsigned long long) (/share/dim/src/misc/hw+0x806f163)
    #1 0x805dce3 in __sanitizer::CheckFailed(char const*, int, char const, unsigned long long, unsigned long long) (/share/dim/src/misc/hw+0x805dce3)
    #2 0x80dfc65 in __asan::PoisonShadow(unsigned long, unsigned long, unsigned char) (/share/dim/src/misc/hw+0x80dfc65)
    #3 0x80696dd in __asan::AsanThread::Init(void) (/share/dim/src/misc/hw+0x80696dd)
    #4 0x806997f in __asan::AsanThread::ThreadStart(unsigned long, __sanitizer::atomic_uintptr_t*) (/share/dim/src/misc/hw+0x806997f)
    #5 0x806ecf3 in __asan::AsanInitInternal(void) (/share/dim/src/misc/hw+0x806ecf3)
    #6 0x8092785 in clock_gettime (/share/dim/src/misc/hw+0x8092785)

When I put some printfs in there, it showed that the expected address granularity is 8, but the address to be checked was aligned on 4 bytes:

DBG: addr=0x284429f4, granularity=8

Tracing back the definitions, I found:

#define SHADOW_GRANULARITY (1ULL << SHADOW_SCALE)

then:

#define SHADOW_SCALE kDefaultShadowScale


then:

static const u64 kDefaultShadowScale = 3;

So this seems to be hardcoded.  There is a similar declaration in llvm's lib/Transforms/Instrumentation/AddressSanitizer.cpp.

I know that it *did* work at some point in the past, but it got broken in recent history.  I will have to do some archeology to figure out what happened.

Does anybody know whether the shadow granularity was different at some point?

-Dimitry

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