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Filename Latest commit message Latest commit date
Thomas Gleixner 6879298bd0 x86/entry/64: Prevent clobbering of saved CR2 value
The recent fix for CR2 corruption introduced a new way to reliably corrupt
the saved CR2 value.

CR2 is saved early in the entry code in RDX, which is the third argument to
the fault handling functions. But it missed that between saving and
invoking the fault handler enter_from_user_mode() can be called. RDX is a
caller saved register so the invoked function can freely clobber it with
the obvious consequences.

The TRACE_IRQS_OFF call is safe as it calls through the thunk which
preserves RDX, but TRACE_IRQS_OFF_DEBUG is not because it also calls into
C-code outside of the thunk.

Store CR2 in R12 instead which is a callee saved register and move R12 to
RDX just before calling the fault handler.

Fixes: a0d14b8909 ("x86/mm, tracing: Fix CR2 corruption")
Reported-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1907201020540.1782@nanos.tec.linutronix.de
2019-07-20 14:28:41 +02:00
arch x86/entry/64: Prevent clobbering of saved CR2 value 2019-07-20 14:28:41 +02:00
block
certs
crypto USB / PHY patches for 5.3-rc1 2019-07-11 15:40:06 -07:00
Documentation HMM patches for 5.3 2019-07-14 19:42:11 -07:00
drivers HMM patches for 5.3 2019-07-14 19:42:11 -07:00
fs HMM patches for 5.3 2019-07-14 19:42:11 -07:00
include HMM patches for 5.3 2019-07-14 19:42:11 -07:00
init Kbuild updates for v5.3 2019-07-12 16:03:16 -07:00
ipc
kernel HMM patches for 5.3 2019-07-14 19:42:11 -07:00
lib Merge branch 'for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu 2019-07-14 16:17:18 -07:00
LICENSES
mm HMM patches for 5.3 2019-07-14 19:42:11 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-07-13 15:57:37 -07:00
samples Kbuild updates for v5.3 2019-07-12 16:03:16 -07:00
scripts stream_open related bits for Linux 5.3 2019-07-14 17:08:08 -07:00
security Merge branch 'akpm' (patches from Andrew) 2019-07-12 11:40:28 -07:00
sound Driver Core and debugfs changes for 5.3-rc1 2019-07-12 12:24:03 -07:00
tools Revert "x86/ptrace: Prevent ptrace from clearing the FS/GS selector" and fix the test 2019-07-15 17:12:31 +02:00
usr
virt ARM: 2019-07-12 15:35:14 -07:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
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COPYING
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Kconfig
MAINTAINERS MAINTAINERS: Update PARAVIRT_OPS_INTERFACE and VMWARE_HYPERVISOR_INTERFACE 2019-07-17 00:42:27 +02:00
Makefile Kbuild updates for v5.3 2019-07-12 16:03:16 -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.

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.