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Dave Hansen a44ca8f5a3 x86/pti: Reduce amount of kernel text allowed to be Global
commit abb67605203687c8b7943d760638d0301787f8d9

Kees reported to me that I made too much of the kernel image global.
It was far more than just text:

	I think this is too much set global: _end is after data,
	bss, and brk, and all kinds of other stuff that could
	hold secrets. I think this should match what
	mark_rodata_ro() is doing.

This does exactly that.  We use __end_rodata_hpage_align as our
marker both because it is huge-page-aligned and it does not contain
any sections we expect to hold secrets.

Kees's logic was that r/o data is in the kernel image anyway and,
in the case of traditional distributions, can be freely downloaded
from the web, so there's no reason to hide it.

Fixes: 8c06c7740 (x86/pti: Leave kernel text global for !PCID)
Reported-by: Kees Cook <keescook@google.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Link: https://lkml.kernel.org/r/20180420222023.1C8B2B20@viggo.jf.intel.com
2018-04-25 11:02:50 +02:00
arch x86/pti: Reduce amount of kernel text allowed to be Global 2018-04-25 11:02:50 +02:00
block
certs
crypto
Documentation
drivers exynos, i915, vc4, amdgpu fixes 2018-04-22 17:14:29 -07:00
firmware
fs various SMB3/CIFS fixes for stable 4.17-rc1 2018-04-22 12:13:04 -07:00
include exynos, i915, vc4, amdgpu fixes 2018-04-22 17:14:29 -07:00
init
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lib
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samples
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tools
usr
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Makefile Linux 4.17-rc2 2018-04-22 19:20:09 -07:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.