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Filename Latest commit message Latest commit date
Gerald Schaefer a76ce01ec9 s390/mm: properly clear _PAGE_NOEXEC bit when it is not supported
commit ab874f22d35a8058d8fdee5f13eb69d8867efeae upstream.

On older HW or under a hypervisor, w/o the instruction-execution-
protection (IEP) facility, and also w/o EDAT-1, a translation-specification
exception may be recognized when bit 55 of a pte is one (_PAGE_NOEXEC).

The current code tries to prevent setting _PAGE_NOEXEC in such cases,
by removing it within set_pte_at(). However, ptep_set_access_flags()
will modify a pte directly, w/o using set_pte_at(). There is at least
one scenario where this can result in an active pte with _PAGE_NOEXEC
set, which would then lead to a panic due to a translation-specification
exception (write to swapped out page):

do_swap_page
  pte = mk_pte (with _PAGE_NOEXEC bit)
  set_pte_at   (will remove _PAGE_NOEXEC bit in page table, but keep it
                in local variable pte)
  vmf->orig_pte = pte (pte still contains _PAGE_NOEXEC bit)
  do_wp_page
    wp_page_reuse
      entry = vmf->orig_pte (still with _PAGE_NOEXEC bit)
      ptep_set_access_flags (writes entry with _PAGE_NOEXEC bit)

Fix this by clearing _PAGE_NOEXEC already in mk_pte_phys(), where the
pgprot value is applied, so that no pte with _PAGE_NOEXEC will ever be
visible, if it is not supported. The check in set_pte_at() can then also
be removed.

Cc: <stable@vger.kernel.org> # 4.11+
Fixes: 57d7f939e7 ("s390: add no-execute support")
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-12-17 19:56:16 +01:00
arch s390/mm: properly clear _PAGE_NOEXEC bit when it is not supported 2019-12-17 19:56:16 +01:00
block blk-mq: avoid sysfs buffer overflow with too many CPU cores 2019-12-17 19:56:14 +01:00
certs
crypto crypto: user - fix memory leak in crypto_reportstat 2019-12-13 08:43:11 +01:00
Documentation USB: documentation: flags on usb-storage versus UAS 2019-12-17 19:55:32 +01:00
drivers ar5523: check NULL before memcpy() in ar5523_cmd() 2019-12-17 19:56:16 +01:00
fs ovl: relax WARN_ON() on rename to self 2019-12-17 19:56:11 +01:00
include compat_ioctl: add compat_ptr_ioctl() 2019-12-17 19:55:30 +01:00
init
ipc
kernel cgroup: pids: use atomic64_t for pids->limit 2019-12-17 19:56:15 +01:00
lib lib: raid6: fix awk build warnings 2019-12-17 19:56:09 +01:00
LICENSES
mm
net rfkill: allocate static minor 2019-12-13 08:43:18 +01:00
samples
scripts
security
sound ASoC: fsl_audmix: Add spin lock to protect tdms 2019-12-17 19:56:14 +01:00
tools kselftest: Fix NULL INSTALL_PATH for TARGETS runlist 2019-12-13 08:43:31 +01:00
usr
virt KVM: arm/arm64: vgic: Don't rely on the wrong pending table 2019-12-13 08:43:00 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-22 14:28:14 -08:00
Makefile Linux 5.4.3 2019-12-13 08:43:32 +01:00
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.