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Re: glibc 2.24 -- Release blockers


On Fri, Jul 15, 2016 at 01:47:33PM +0200, Florian Weimer wrote:
> 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?

I mean setarch(8) is not versatile enough, it just rewrites personality
flags.  For example,

$ strace -qq -epersonality \
  setarch linux64 --sticky-timeouts setarch linux64 --addr-no-randomize true
personality(PER_LINUX|STICKY_TIMEOUTS)  = 0 (PER_LINUX)
personality(PER_LINUX|ADDR_NO_RANDOMIZE) = 0x4000000 (PER_LINUX|STICKY_TIMEOUTS)


-- 
ldv

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