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Kirill A. Shutemov 81c7ed296d x86/boot/64: Fix crash if kernel image crosses page table boundary
A kernel which boots in 5-level paging mode crashes in a small percentage
of cases if KASLR is enabled.

This issue was tracked down to the case when the kernel image unpacks in a
way that it crosses an 1G boundary. The crash is caused by an overrun of
the PMD page table in __startup_64() and corruption of P4D page table
allocated next to it. This particular issue is not visible with 4-level
paging as P4D page tables are not used.

But the P4D and the PUD calculation have similar problems.

The PMD index calculation is wrong due to operator precedence, which fails
to confine the PMDs in the PMD array on wrap around.

The P4D calculation for 5-level paging and the PUD calculation calculate
the first index correctly, but then blindly increment it which causes the
same issue when a kernel image is located across a 512G and for 5-level
paging across a 46T boundary.

This wrap around mishandling was introduced when these parts moved from
assembly to C.

Restore it to the correct behaviour.

Fixes: c88d71508e ("x86/boot/64: Rewrite startup_64() in C")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190620112345.28833-1-kirill.shutemov@linux.intel.com
2019-06-26 07:25:09 +02:00
arch x86/boot/64: Fix crash if kernel image crosses page table boundary 2019-06-26 07:25:09 +02:00
block block: print offending values when cloned rq limits are exceeded 2019-05-31 15:12:34 -06:00
certs treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
crypto treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
Documentation mm, memcg: consider subtrees in memory.events 2019-06-01 15:51:31 -07:00
drivers Merge branch 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-02 11:06:13 -07:00
fs for-linus-20190601 2019-06-02 09:27:44 -07:00
include x86/microcode, cpuhotplug: Add a microcode loader CPU hotplug callback 2019-06-15 10:00:29 +02:00
init treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 167 2019-05-30 11:26:39 -07:00
ipc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 52 2019-05-24 17:36:42 +02:00
kernel Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-02 11:08:12 -07:00
lib SPDX fixes for 5.2-rc3, round 2 2019-06-02 10:22:38 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/vmalloc: Avoid rare case of flushing TLB with weird arguments 2019-06-03 11:47:25 +02:00
net SPDX update for 5.2-rc3, round 1 2019-05-31 08:34:32 -07:00
samples treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 206 2019-05-30 11:29:53 -07:00
scripts Merge branch 'akpm' (patches from Andrew) 2019-06-02 08:51:30 -07:00
security Merge branch 'next-fixes-for-5.2-rc' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2019-05-31 11:08:44 -07:00
sound treewide: fix typos of SPDX-License-Identifier 2019-06-01 18:29:58 +02:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-02 11:08:12 -07:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt Fixes for PPC and s390. 2019-06-02 10:19:39 -07:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore .gitignore: exclude .get_maintainer.ignore and .gitattributes 2019-05-18 11:49:54 +09:00
.mailmap A reasonably busy cycle for docs, including: 2019-05-08 12:42:50 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Farewell Martin Schwidefsky 2019-05-31 10:14:11 +02:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2019-06-02 10:18:11 -07:00
Makefile Linux 5.2-rc3 2019-06-02 13:55:33 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.

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.