[llvm] r243934 - [UB] Fix yet another use of memcpy with a null pointer argument. I think

[Hans Wennborg via llvm-commits]

Merged in r244224.


On Mon, Aug 3, 2015 at 6:17 PM, Chandler Carruth <chandlerc at gmail.com> wrote:
> Should probably pull this into the release as it fixes something that could
> miscompile in the future with a new host compiler.
>
>
> On Mon, Aug 3, 2015 at 6:05 PM Chandler Carruth <chandlerc at gmail.com> wrote:
>>
>> Author: chandlerc
>> Date: Mon Aug  3 20:00:56 2015
>> New Revision: 243934
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=243934&view=rev
>> Log:
>> [UB] Fix yet another use of memcpy with a null pointer argument. I think
>> this is the last of them in my build of LLVM. Haven't tried Clang yet.
>>
>> Found via UBSan.
>>
>> Modified:
>>     llvm/trunk/lib/Support/MemoryBuffer.cpp
>>
>> Modified: llvm/trunk/lib/Support/MemoryBuffer.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/MemoryBuffer.cpp?rev=243934&r1=243933&r2=243934&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Support/MemoryBuffer.cpp (original)
>> +++ llvm/trunk/lib/Support/MemoryBuffer.cpp Mon Aug  3 20:00:56 2015
>> @@ -57,7 +57,8 @@ void MemoryBuffer::init(const char *BufS
>>  /// CopyStringRef - Copies contents of a StringRef into a block of memory
>> and
>>  /// null-terminates it.
>>  static void CopyStringRef(char *Memory, StringRef Data) {
>> -  memcpy(Memory, Data.data(), Data.size());
>> +  if (!Data.empty())
>> +    memcpy(Memory, Data.data(), Data.size());
>>    Memory[Data.size()] = 0; // Null terminate string.
>>  }
>>
>>
>>
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