[llvm-commits] [LLVMdev] [PATCH] Add the disable_aslr option that will disable the address space layout randomization under AddressSanitizer on 10.6

[Kostya Serebryany]

On Fri, Dec 9, 2011 at 11:24 AM, Eric Christopher <echristo at apple.com>wrote:

>
> On Dec 9, 2011, at 11:23 AM, Kostya Serebryany wrote:
>
>
>
> On Fri, Dec 9, 2011 at 11:16 AM, Eric Christopher <echristo at apple.com>wrote:
>
>>
>> On Dec 9, 2011, at 11:12 AM, Kostya Serebryany wrote:
>>
>> > Yes, we have no ASRL with -no_pie.
>> > Can we disable ASRL even with -pie?
>> > On linux we can do it with "setarch x86_64 -R".
>> >
>>
>> You asked about link time. Now it sounds like you're talking about
>> runtime?
>>
>
> Link time is of course better.
> But if there is a syscall (like the one used by setarch) we could call it
> and reexec.
> Using setenv("DYLD_NO_PIE")+reexec looks gross to me.
>
>
>
> Not sure honestly.
>

Thanks. If anyone knows, please jump in.

As for the patch, I really don't like
  1. 3 different cases for 3 different flavors of MacOS. How are we goring
to support it?
  2. doing setenv+reexec. This will be a debugging nightmare for us and for
users.

I would prefer just to print a descriptive warning message and exit:
   ==123== ERROR: AddressSanitizer on MacOS requires to disable ASRL for
the executable.
   ==123== ERROR: You can do it this way:
   ==123== ERROR: <how to disable ASLR>
   ==123== ABORTING

--kcc



>
>
>> > Another question: if asan would require -no_pie on Mac, will this be a
>> serious limitation?
>> >
>>
>> If asan required no pie on Linux, would it be a serious limitation?
>>
>
> For Linux, I don't think this will be too bad, but may cause some users a
> bit of pain to rework their build files.
> Luckily, asan and -pie work together on Linux quite well.
> I don't know how important is "-pie" on Mac.
>
>
> Just as important as it is on Linux.
>
> -eric
>
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