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Date:      Sun, 25 May 2014 20:06:40 +0200
From:      Dimitry Andric <dim@FreeBSD.org>
To:        Oliver Pinter <oliver.pntr@gmail.com>
Cc:        freebsd-security@freebsd.org, =?iso-8859-1?Q?Dag-Erling_Sm=F8rgrav?= <des@des.no>, freebsd-current@freebsd.org, freebsd-stable@freebsd.org, Shawn Webb <lattera@gmail.com>
Subject:   Re: [CFT] ASLR, PIE, and segvguard on 11-current and 10-stable
Message-ID:  <49702223-7624-4D44-9371-2F8C5E2D4D38@FreeBSD.org>
In-Reply-To: <CAPjTQNE6V%2BMAMg4KODVhLckq9p=kpKZPmSK=LEtQkcfZqVi7SA@mail.gmail.com>
References:  <20140514135852.GC3063@pwnie.vrt.sourcefire.com> <CAPjTQNG9pGLbDF7a8b%2B9s_NRD3Rq-sLnj7AXczjB=Ko_S44C3A@mail.gmail.com> <86a9a56ac6.fsf@nine.des.no> <CAPjTQNE6V%2BMAMg4KODVhLckq9p=kpKZPmSK=LEtQkcfZqVi7SA@mail.gmail.com>

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On 25 May 2014, at 19:42, Oliver Pinter <oliver.pntr@gmail.com> wrote:
> On 5/25/14, Dag-Erling Sm=F8rgrav <des@des.no> wrote:
>> Oliver Pinter <oliver.pntr@gmail.com> writes:
...
>>>      PAX: blacklist clang and related binaries from PIE support
>>=20
>> Why?  Performance, or do they actually break?
>=20
> No. If you definded WITH_CLANG_EXTRAS=3D in src.conf, the breaked the =
build.
> (added dim@ to CC)
>=20
> --- usr.bin.all__D ---
> =
/usr/obj/usr/data/source/git/opBSD/hardenedBSD.git/usr.bin/clang/bugpoint/=
../../../lib/clang/libllvmirreader/libllvmirreader.a:
> could not read symbols: Bad value
> c++: error: linker command failed with exit code 1 (use -v to see =
invocation)
> *** [bugpoint] Error code 1

I assume you only get this with your ASLR patches applied?  Maybe this =
is because the clang binary itself gets built statically (and so will =
definitely not be PIE), but the rest of the 'extras', such as bugpoint, =
are regular dynamic executables.  And note that none of the libraries =
built under lib/libclang are built with -fPIC, at the moment.  So that =
might cause trouble with your PIE patches.

In any case, the interesting thing is what the actual linker error was.  =
Do you have more of the preceding build log, including the rest of the =
settings that were used to build world?  And also, what does "file =
/usr/obj/usr/data/source/git/opBSD/hardenedBSD.git/usr.bin/clang/bugpoint/=
../../../lib/clang/libllvmirreader/libllvmirreader.a" say?

-Dimitry


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