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From: "jyescas at google dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug dynamic-link/31076] Extra struct vm_area_struct with ---p
 created when PAGE_SIZE < max-page-size
Date: Mon, 27 Nov 2023 19:55:18 +0000
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D31076

--- Comment #13 from Juan Yescas <jyescas at google dot com> ---
> > Right, but my point is if this is a hardening feature that glibc aims to
> > provide it does not help if the kernel still does not provide it for the
> > loader (if this is built with a different page size) and the main progr=
am
> > itself. Should we push for kernel to implement a similar handling?
>=20
> The kernel effectively implements the munmap behavior, I think. It creates
> unmapped holes, not PROT_MEM reserved holes.

That is right. The kernel vm_munmap the holes for the program image and dyn=
amic
linker image:

Code that vm_munmap the holes.
https://elixir.bootlin.com/linux/v6.6.2/source/fs/binfmt_elf.c#L397

Code that loads the program image segments.
https://elixir.bootlin.com/linux/v6.6.2/source/fs/binfmt_elf.c#L1165

Code that loads the dynamic linker segments.
https://elixir.bootlin.com/linux/v6.6.2/source/fs/binfmt_elf.c#L397

--=20
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