[llvm] r220567 - [Object] Fix MachO's getUuid to return a pointer into the object instead of a dangling ArrayRef.

[Alexey Samsonov]

Thanks for fixing this!

On Fri, Oct 24, 2014 at 8:52 AM, Benjamin Kramer <benny.kra at googlemail.com>
wrote:

> Author: d0k
> Date: Fri Oct 24 10:52:05 2014
> New Revision: 220567
>
> URL: http://llvm.org/viewvc/llvm-project?rev=220567&view=rev
> Log:
> [Object] Fix MachO's getUuid to return a pointer into the object instead
> of a dangling ArrayRef.
>
> This works because uuid's are always little endian so it's not swapped.
> Fixes use-after-return reported by asan.
>
> Modified:
>     llvm/trunk/lib/Object/MachOObjectFile.cpp
>
> Modified: llvm/trunk/lib/Object/MachOObjectFile.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Object/MachOObjectFile.cpp?rev=220567&r1=220566&r2=220567&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/Object/MachOObjectFile.cpp (original)
> +++ llvm/trunk/lib/Object/MachOObjectFile.cpp Fri Oct 24 10:52:05 2014
> @@ -2460,8 +2460,9 @@ ArrayRef<uint8_t> MachOObjectFile::getDy
>  ArrayRef<uint8_t> MachOObjectFile::getUuid() const {
>    if (!UuidLoadCmd)
>      return ArrayRef<uint8_t>();
> -  MachO::uuid_command Uuid = getStruct<MachO::uuid_command>(this,
> UuidLoadCmd);
> -  return ArrayRef<uint8_t>(Uuid.uuid, 16);
> +  // Returning a pointer is fine as uuid doesn't need endian swapping.
> +  const char *Ptr = UuidLoadCmd + offsetof(MachO::uuid_command, uuid);
> +  return ArrayRef<uint8_t>(reinterpret_cast<const uint8_t *>(Ptr), 16);
>  }
>
>  StringRef MachOObjectFile::getStringTableData() const {
>
>
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-- 
Alexey Samsonov
vonosmas at gmail.com
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