[llvm] r180094 - Tell MSan that memory initialized by libz is valid

[Nick Lewycky]

On 04/23/2013 05:17 AM, Alexey Samsonov wrote:
> Author: samsonov
> Date: Tue Apr 23 07:17:46 2013
> New Revision: 180094
>
> URL: http://llvm.org/viewvc/llvm-project?rev=180094&view=rev
> Log:
> Tell MSan that memory initialized by libz is valid

Why doesn't msan instrument this correctly? Or is libz not initializing 
all this memory?

Nick

>
> Modified:
>      llvm/trunk/lib/Support/Compression.cpp
>
> Modified: llvm/trunk/lib/Support/Compression.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Compression.cpp?rev=180094&r1=180093&r2=180094&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Support/Compression.cpp (original)
> +++ llvm/trunk/lib/Support/Compression.cpp Tue Apr 23 07:17:46 2013
> @@ -15,6 +15,7 @@
>   #include "llvm/ADT/OwningPtr.h"
>   #include "llvm/ADT/StringRef.h"
>   #include "llvm/Config/config.h"
> +#include "llvm/Support/Compiler.h"
>   #include "llvm/Support/ErrorHandling.h"
>   #include "llvm/Support/MemoryBuffer.h"
>   #if LLVM_ENABLE_ZLIB == 1&&  HAVE_ZLIB_H
> @@ -55,9 +56,12 @@ zlib::Status zlib::compress(StringRef In
>     Status Res = encodeZlibReturnValue(::compress2(
>         (Bytef *)TmpBuffer.get(),&CompressedSize,
>         (const Bytef *)InputBuffer.data(), InputBuffer.size(), CLevel));
> -  if (Res == StatusOK)
> +  if (Res == StatusOK) {
>       CompressedBuffer.reset(MemoryBuffer::getMemBufferCopy(
>           StringRef(TmpBuffer.get(), CompressedSize)));
> +    // Tell MSan that memory initialized by zlib is valid.
> +    __msan_unpoison(CompressedBuffer.data(), CompressedBuffer.size());
> +  }
>     return Res;
>   }
>
> @@ -68,9 +72,12 @@ zlib::Status zlib::uncompress(StringRef
>     Status Res = encodeZlibReturnValue(
>         ::uncompress((Bytef *)TmpBuffer.get(), (uLongf *)&UncompressedSize,
>                      (const Bytef *)InputBuffer.data(), InputBuffer.size()));
> -  if (Res == StatusOK)
> +  if (Res == StatusOK) {
>       UncompressedBuffer.reset(MemoryBuffer::getMemBufferCopy(
>           StringRef(TmpBuffer.get(), UncompressedSize)));
> +    // Tell MSan that memory initialized by zlib is valid.
> +    __msan_unpoison(UncompressedBuffer.data(), UncompressedBuffer.size());
> +  }
>     return Res;
>   }
>
>
>
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