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Re: glibc 2.24 -- Release blockers


On 07/15/2016 01:32 PM, Dmitry V. Levin wrote:
On Fri, Jul 15, 2016 at 12:52:33PM +0200, Florian Weimer wrote:
On 07/15/2016 02:45 AM, Paul Eggert wrote:
On 07/14/2016 01:27 PM, Florian Weimer wrote:
GDB does this to disable randomization:

Thanks. Emacs disables ASLR by invoking the 'setfattr -n user.pax.flags
-v er' shell command on the Emacs executable before running it ('paxctl
+a' on older systems). Does this approach not work on ppc64? If not,
what shell command would work?

I have never seen these commands before.  On mainline Linux, you need to
use setarch (perhaps from a shell script wrapper), and this calls
personality internally.

One has to use personality(personality(0xffffffff)|ADDR_NO_RANDOMIZE)
approach as implemented in GDB, a simple shell script wrapper cannot
implement this.

Would you please elaborate?

In my testing, the ADDR_NO_RANDOMIZE bit is inherited by subprocesses (which is a problem in itself, of course, because it disables hardening in network helpers used by Emacs).

Thanks,
Florian


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