bugThe GNU Hurd - Bugs: bug #17646, glibc: ``-z relro''

 
 

bug #17646: glibc: ``-z relro''

Submitted by:  Thomas Schwinge <tschwinge>
Submitted on:  Fri 08 Sep 2006 08:37:54 AM UTC  
 
Category: glibcSeverity: 4 - Important
Priority: 7 - HighItem Group: None
Status: FixedPrivacy: Public
Assigned to: Samuel Thibault <sthibaul>Originator Name: 
Open/Closed: ClosedReproducibility: Every Time
Size (loc): NonePlanned Release: None
Effort: 0.00
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Fri 17 Apr 2009 09:08:12 AM UTC, comment #7:

Samuel would eventually also hit this relro problem, but then also come up with a fix: <http://sourceware.org/ml/libc-alpha/2009-04/msg00003.html>

Thomas Schwinge <tschwinge>
Project Administrator
Sun 10 Jun 2007 03:39:03 PM UTC, comment #6:

I've just tried re-compiling hurd with a relro-enabled glibc, and it boots just fine. I tried to compile a package, no problem either.

Samuel Thibault <sthibaul>
Project MemberIn charge of this item.
Sun 10 Jun 2007 08:34:17 AM UTC, comment #5:

No, I haven't tried 2.6, precisely because it needs other changes. I preferred to start with a working -z relro -enabled 2.5 before moving to 2.6

Anonymous
Sat 09 Jun 2007 08:34:40 AM UTC, comment #4:

glibc 2.6 indeed needs (a lot) more work to make it usable on Hurd systems. The thing glibc 2.6 changed w.r.t. ``-z relro'' was ``only'' that it is no longer possible to switch it off via the command line ``libc_cv_z_relro=no''.

For me, the (only!) test case that illustrates the problem was to use a ``-z relro'' enabled glibc to build the Hurd servers, boot a system with those (e.g. a subhurd) and then one of the core Hurd servers (perhaps the root file system, but I don't remember at the moment) would segfault (also not sure about that, but that's what it was, I think). I once was spending some time working on debugging that, but didn't find the cause of the segfault so far. I think I took some notes about what I did, in case you are interested.

Thomas Schwinge <tschwinge>
Project Administrator
Fri 08 Jun 2007 09:06:25 PM UTC, comment #3:

If I'm not wrong 2.5 got released a couple of days before this change, my glibc-2.5 tarball doesn't seem to have the change Thomas referenced in comment #1.

Did you try with glibc-2.6 from experimental instead (though more work is probably needed there to get it built)?

Michael Banck <mbanck>
Fri 08 Jun 2007 06:59:06 PM UTC, comment #2:

Which testcase makes the dynamic loader crash? I tried compiling 2.5 with z_relro, I am currently using it, and it seems to work fine. People can try a debian package from my repo at http://dept-info.labri.fr/~thibault/debian-hurd main unstable

Samuel Thibault <sthibaul>
Project MemberIn charge of this item.
Mon 06 Nov 2006 03:48:50 PM UTC, comment #1:

The hack of configuring glibc with ``libc_cv_z_relro=no'' to get an usable result will not work anymore with glibc trunk versions that are newer than 2006-10-28: <http://sourceware.org/ml/glibc-cvs/2006-q4/msg00202.html>.

Thomas Schwinge <tschwinge>
Project Administrator
Fri 08 Sep 2006 08:37:54 AM UTC, original submission:

Binutils 2.16 introduced ``-z relro'', which glibc uses if available and which makes the dynamic loader crash on GNU/Hurd, probably because it is somewhere being used too restrictively.

We currently work around that by specifying ``libc_cv_z_relro=no'' when configuring glibc.

Thomas Schwinge <tschwinge>
Project Administrator

 

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    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Fri 17 Apr 2009 09:08:12 AM UTCtschwingeStatusNone=>Fixed
      Assigned toNone=>sthibaul
      Open/ClosedOpen=>Closed

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