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Ard Biesheuvel 8319e9d5ad efi/x86: Handle by-ref arguments covering multiple pages in mixed mode
The mixed mode runtime wrappers are fragile when it comes to how the
memory referred to by its pointer arguments are laid out in memory, due
to the fact that it translates these addresses to physical addresses that
the runtime services can dereference when running in 1:1 mode. Since
vmalloc'ed pages (including the vmap'ed stack) are not contiguous in the
physical address space, this scheme only works if the referenced memory
objects do not cross page boundaries.

Currently, the mixed mode runtime service wrappers require that all by-ref
arguments that live in the vmalloc space have a size that is a power of 2,
and are aligned to that same value. While this is a sensible way to
construct an object that is guaranteed not to cross a page boundary, it is
overly strict when it comes to checking whether a given object violates
this requirement, as we can simply take the physical address of the first
and the last byte, and verify that they point into the same physical page.

When this check fails, we emit a WARN(), but then simply proceed with the
call, which could cause data corruption if the next physical page belongs
to a mapping that is entirely unrelated.

Given that with vmap'ed stacks, this condition is much more likely to
trigger, let's relax the condition a bit, but fail the runtime service
call if it does trigger.

Fixes: f6697df36b ("x86/efi: Prevent mixed mode boot corruption with CONFIG_VMAP_STACK=y")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: linux-efi@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200221084849.26878-4-ardb@kernel.org
2020-02-26 15:31:42 +01:00
arch efi/x86: Handle by-ref arguments covering multiple pages in mixed mode 2020-02-26 15:31:42 +01:00
block block-5.6-2020-02-05 2020-02-06 06:15:23 +00:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
Documentation Bugfixes, including the fix for CVE-2020-2732 and a few 2020-02-24 11:48:17 -08:00
drivers Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-02-24 11:40:23 -08:00
fs for-5.6-rc2-tag 2020-02-23 09:43:50 -08:00
include Bugfixes, including the fix for CVE-2020-2732 and a few 2020-02-24 11:48:17 -08:00
init Various fixes: 2020-02-11 16:39:18 -08:00
ipc Revert "ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()" 2020-02-21 11:22:15 -08:00
kernel Two fixes for the irq core code which are follow ups to the recent MSI 2020-02-22 17:25:46 -08:00
lib Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-02-24 11:40:23 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-02-24 11:32:15 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-02-21 11:59:51 -08:00
samples Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
scripts scripts/get_maintainer.pl: deprioritize old Fixes: addresses 2020-02-21 11:22:15 -08:00
security Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2020-02-20 15:15:16 -08:00
sound ASoC: Fixes for v5.6 2020-02-18 13:33:39 +01:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-02-21 11:59:51 -08:00
usr Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
virt KVM: Disable preemption in kvm_get_running_vcpu() 2020-02-12 12:19:35 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap A handful of small documentation fixes that wandered in. 2020-02-07 13:03:10 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Hand MIPS over to Thomas 2020-02-24 22:43:18 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge branch 'mips-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux 2020-02-25 10:09:41 -08:00
Makefile Linux 5.6-rc3 2020-02-23 16:17:42 -08:00
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.