[llvm-commits] [compiler-rt] r168046 - in /compiler-rt/trunk/lib/asan: asan_allocator.cc asan_internal.h asan_report.cc asan_thread.cc

[Alexey Samsonov]

This fix is completely wrong: FakeStack::AddrIsInFakeStack(addr)
doesn't return a fake stack frame containing "addr", but a pointer to
a mapped memory region containing a bunch of fake stack frames of the same
size.

On Thu, Nov 15, 2012 at 7:45 PM, Kostya Serebryany <kcc at google.com> wrote:

> Thanks!
>
>
> On Thu, Nov 15, 2012 at 7:24 AM, Alexander Potapenko <glider at google.com>wrote:
>
>> Author: glider
>> Date: Thu Nov 15 09:24:42 2012
>> New Revision: 168046
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=168046&view=rev
>> Log:
>> [ASan] Revert r168040 and r168043 and take a cleaner solution suggested
>> by Kostya: return the known frame name for fake stack instead of looking it
>> up.
>>
>> Modified:
>>     compiler-rt/trunk/lib/asan/asan_allocator.cc
>>     compiler-rt/trunk/lib/asan/asan_internal.h
>>     compiler-rt/trunk/lib/asan/asan_report.cc
>>     compiler-rt/trunk/lib/asan/asan_thread.cc
>>
>> Modified: compiler-rt/trunk/lib/asan/asan_allocator.cc
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_allocator.cc?rev=168046&r1=168045&r2=168046&view=diff
>>
>> ==============================================================================
>> --- compiler-rt/trunk/lib/asan/asan_allocator.cc (original)
>> +++ compiler-rt/trunk/lib/asan/asan_allocator.cc Thu Nov 15 09:24:42 2012
>> @@ -998,10 +998,6 @@
>>    CHECK(fake_frame->descr != 0);
>>    CHECK(fake_frame->size_minus_one == size - 1);
>>    PoisonShadow(ptr, size, kAsanStackAfterReturnMagic);
>> -  CHECK(size >= SHADOW_GRANULARITY);
>> -  // Poison the leftmost shadow byte with a special value so that we can
>> find
>> -  // the beginning of the fake frame when reporting an error.
>> -  PoisonShadow(ptr, SHADOW_GRANULARITY, kAsanStackAfterReturnLeftMagic);
>>  }
>>
>>  }  // namespace __asan
>>
>> Modified: compiler-rt/trunk/lib/asan/asan_internal.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_internal.h?rev=168046&r1=168045&r2=168046&view=diff
>>
>> ==============================================================================
>> --- compiler-rt/trunk/lib/asan/asan_internal.h (original)
>> +++ compiler-rt/trunk/lib/asan/asan_internal.h Thu Nov 15 09:24:42 2012
>> @@ -160,7 +160,6 @@
>>  const int kAsanStackAfterReturnMagic = 0xf5;
>>  const int kAsanInitializationOrderMagic = 0xf6;
>>  const int kAsanUserPoisonedMemoryMagic = 0xf7;
>> -const int kAsanStackAfterReturnLeftMagic = 0xf8;
>>  const int kAsanGlobalRedzoneMagic = 0xf9;
>>  const int kAsanInternalHeapMagic = 0xfe;
>>
>>
>> Modified: compiler-rt/trunk/lib/asan/asan_report.cc
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_report.cc?rev=168046&r1=168045&r2=168046&view=diff
>>
>> ==============================================================================
>> --- compiler-rt/trunk/lib/asan/asan_report.cc (original)
>> +++ compiler-rt/trunk/lib/asan/asan_report.cc Thu Nov 15 09:24:42 2012
>> @@ -450,7 +450,6 @@
>>          bug_descr = "stack-buffer-overflow";
>>          break;
>>        case kAsanStackAfterReturnMagic:
>> -      case kAsanStackAfterReturnLeftMagic:
>>          bug_descr = "stack-use-after-return";
>>          break;
>>        case kAsanUserPoisonedMemoryMagic:
>>
>> Modified: compiler-rt/trunk/lib/asan/asan_thread.cc
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_thread.cc?rev=168046&r1=168045&r2=168046&view=diff
>>
>> ==============================================================================
>> --- compiler-rt/trunk/lib/asan/asan_thread.cc (original)
>> +++ compiler-rt/trunk/lib/asan/asan_thread.cc Thu Nov 15 09:24:42 2012
>> @@ -118,41 +118,35 @@
>>
>>  const char *AsanThread::GetFrameNameByAddr(uptr addr, uptr *offset) {
>>    uptr bottom = 0;
>> -  bool is_fake_stack = false;
>>    if (AddrIsInStack(addr)) {
>>      bottom = stack_bottom();
>>    } else {
>>      bottom = fake_stack().AddrIsInFakeStack(addr);
>>      CHECK(bottom);
>> -    is_fake_stack = true;
>> +    *offset = addr - bottom;
>> +    return  (const char *)((uptr*)bottom)[1];
>>    }
>>    uptr aligned_addr = addr & ~(__WORDSIZE/8 - 1);  // align addr.
>>    u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);
>>    u8 *shadow_bottom = (u8*)MemToShadow(bottom);
>>
>>    while (shadow_ptr >= shadow_bottom &&
>> -      *shadow_ptr != kAsanStackLeftRedzoneMagic &&
>> -      *shadow_ptr != kAsanStackAfterReturnLeftMagic) {
>> +         *shadow_ptr != kAsanStackLeftRedzoneMagic) {
>>      shadow_ptr--;
>>    }
>>
>>    while (shadow_ptr >= shadow_bottom &&
>> -      (*shadow_ptr == kAsanStackLeftRedzoneMagic ||
>> -       *shadow_ptr == kAsanStackAfterReturnLeftMagic)) {
>> +         *shadow_ptr == kAsanStackLeftRedzoneMagic) {
>>      shadow_ptr--;
>>    }
>>
>>    if (shadow_ptr < shadow_bottom) {
>> -    // If we're one byte below the fake stack bottom, we've found the
>> frame.
>> -    if (!is_fake_stack || (*shadow_bottom !=
>> kAsanStackAfterReturnLeftMagic)) {
>> -      *offset = 0;
>> -      return "UNKNOWN";
>> -    }
>> +    *offset = 0;
>> +    return "UNKNOWN";
>>    }
>>
>>    uptr* ptr = (uptr*)SHADOW_TO_MEM((uptr)(shadow_ptr + 1));
>> -  CHECK((ptr[0] == kCurrentStackFrameMagic) ||
>> -      (is_fake_stack && ptr[0] == kRetiredStackFrameMagic));
>> +  CHECK(ptr[0] == kCurrentStackFrameMagic);
>>    *offset = addr - (uptr)ptr;
>>    return (const char*)ptr[1];
>>  }
>>
>>
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-- 
Alexey Samsonov, MSK
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