[compiler-rt] r259007 - [cfi] Fix recovery from out-of-bounds vtable error.

[Evgenii Stepanov via llvm-commits]

Thanks, r259085

On Wed, Jan 27, 2016 at 10:27 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
> On Wed, Jan 27, 2016 at 4:37 PM, Evgeniy Stepanov via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>>
>> Author: eugenis
>> Date: Wed Jan 27 18:37:54 2016
>> New Revision: 259007
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=259007&view=rev
>> Log:
>> [cfi] Fix recovery from out-of-bounds vtable error.
>>
>> Modified:
>>     compiler-rt/trunk/lib/cfi/cfi.cc
>>     compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp
>>
>> Modified: compiler-rt/trunk/lib/cfi/cfi.cc
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/cfi/cfi.cc?rev=259007&r1=259006&r2=259007&view=diff
>>
>> ==============================================================================
>> --- compiler-rt/trunk/lib/cfi/cfi.cc (original)
>> +++ compiler-rt/trunk/lib/cfi/cfi.cc Wed Jan 27 18:37:54 2016
>> @@ -306,12 +306,14 @@ ALWAYS_INLINE void CfiSlowPathCommon(u64
>>      // FIXME: call the ubsan handler if DiagData != nullptr?
>>      VReport(1, "CFI: invalid memory region for a check target: %p\n",
>> Ptr);
>>  #ifdef CFI_ENABLE_DIAG
>> -    if (DiagData)
>> +    if (DiagData) {
>>        __ubsan_handle_cfi_check_fail(
>>            reinterpret_cast<__ubsan::CFICheckFailData *>(DiagData),
>>            reinterpret_cast<uptr>(Ptr));
>> -    else
>> +      return;
>> +    } else {
>
>
> Drop the else-after-return, and possibly invert to reduce indentation:
>
>   if (!DiagData)
>     Trap();
>   __ubsaN-handle_...
>
>>
>>        Trap();
>> +    }
>>  #else
>>      Trap();
>>  #endif
>> @@ -348,7 +350,8 @@ void InitializeFlags() {
>>
>>    SetVerbosity(common_flags()->verbosity);
>>
>> -  if (Verbosity()) ReportUnrecognizedFlags();
>> +  if (Verbosity())
>> +    ReportUnrecognizedFlags();
>>
>>    if (common_flags()->help) {
>>      cfi_parser.PrintFlagDescriptions();
>>
>> Modified: compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp?rev=259007&r1=259006&r2=259007&view=diff
>>
>> ==============================================================================
>> --- compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp
>> (original)
>> +++ compiler-rt/trunk/test/cfi/cross-dso/target_out_of_bounds.cpp Wed Jan
>> 27 18:37:54 2016
>> @@ -20,9 +20,13 @@ int main(int argc, char *argv[]) {
>>    // enough to handle unaddressable vtables. TODO: fix this.
>>    void *empty = calloc(1, 128);
>>    uintptr_t v = (uintptr_t)empty + 64;
>> -  A *volatile p = new A();
>> -  for (uintptr_t *q = (uintptr_t *)p; q < (uintptr_t *)(p + 1); ++q)
>> +  char *volatile p = reinterpret_cast<char *>(new A());
>> +  for (uintptr_t *q = (uintptr_t *)p; q < (uintptr_t *)(p + sizeof(A));
>> ++q)
>>      *q = v;
>> +
>> +  // CHECK: runtime error: control flow integrity check for type 'A'
>> failed during cast
>> +  A *volatile pa = reinterpret_cast<A *>(p);
>> +
>>    // CHECK: untime error: control flow integrity check for type 'A'
>> failed during virtual call
>> -  p->f();
>> +  pa->f();
>>  }
>>
>>
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>
>