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Re: glibc 2.24 -- Release blockers


On 07/15/2016 04:28 PM, Sinny Kumari wrote:
On Fri, Jul 15, 2016 at 7:49 PM, Sinny Kumari <ksinny@gmail.com> wrote:
On Fri, Jul 15, 2016 at 6:42 PM, Paul Eggert <eggert@cs.ucla.edu> wrote:
On 07/15/2016 12:52 PM, Florian Weimer wrote:

The problem is that this happens at dump time only, while the issue occurs
when running the dumped Emacs. Furthermore, the personality system call (or
at least ADDR_NO_RANDOMIZE) only applies to new process images, it does not
affected the randomization decisions made at load time for the current
process.


I wrote a revised patch to emacs-25 (attached) which I hope addresses the
former issue, by disabling randomization in both the undumped and dumped
Emacs when Emacs uses its own allocator. Emacs already addresses the latter
issue by re-execing itself when it changes personalities, so this shouldn't
be an issue.

After applying this patch in emacs-25.0.95, it builds and run fine on ppc64(le),
Fedora rawhide. It no longer consumes memory in GB !
For reference, scratch build link is
http://ppc.koji.fedoraproject.org/koji/taskinfo?taskID=3538651

Also, output of "cat /proc/self/personality" inside emacs shell
contains value 00040000

Thanks!

This means that new processes spawned by Emacs will have ASLR disable.

Paul, I think the patch should call personality again after it is active for the Emacs process, to disable it for subprocesses.

Florian


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