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Dan Williams fff76ff5e2 mm: fix devmem_is_allowed() for sub-page System RAM intersections 
commit 2bdce74412 upstream.

Hussam reports:

    I was poking around and for no real reason, I did cat /dev/mem and
    strings /dev/mem.  Then I saw the following warning in dmesg. I saved it
    and rebooted immediately.

     memremap attempted on mixed range 0x000000000009c000 size: 0x1000
     ------------[ cut here ]------------
     WARNING: CPU: 0 PID: 11810 at kernel/memremap.c:98 memremap+0x104/0x170
     [..]
     Call Trace:
      xlate_dev_mem_ptr+0x25/0x40
      read_mem+0x89/0x1a0
      __vfs_read+0x36/0x170

The memremap() implementation checks for attempts to remap System RAM
with MEMREMAP_WB and instead redirects those mapping attempts to the
linear map.  However, that only works if the physical address range
being remapped is page aligned.  In low memory we have situations like
the following:

    00000000-00000fff : Reserved
    00001000-0009fbff : System RAM
    0009fc00-0009ffff : Reserved

...where System RAM intersects Reserved ranges on a sub-page page
granularity.

Given that devmem_is_allowed() special cases any attempt to map System
RAM in the first 1MB of memory, replace page_is_ram() with the more
precise region_intersects() to trap attempts to map disallowed ranges.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199999
Link: http://lkml.kernel.org/r/152856436164.18127.2847888121707136898.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 92281dee82 ("arch: introduce memremap()")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Hussam Al-Tayeb <me@hussam.eu.org>
Tested-by: Hussam Al-Tayeb <me@hussam.eu.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2018-07-03 11:25:03 +02:00
Documentation cxl: Disable prefault_mode in Radix mode 2018-07-03 11:24:51 +02:00
arch mm: fix devmem_is_allowed() for sub-page System RAM intersections 2018-07-03 11:25:03 +02:00
block blk-mq: reinit q->tag_set_list entry only after grace period 2018-06-26 08:06:32 +08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto X.509: unpack RSA signatureValue field from BIT STRING 2018-07-03 11:24:57 +02:00
drivers rbd: flush rbd_dev->watch_dwork after watch is unregistered 2018-07-03 11:25:03 +02:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs NFSv4: Fix a typo in nfs41_sequence_process 2018-07-03 11:25:02 +02:00
include IB/hfi1: Optimize kthread pointer locking when queuing CQ entries 2018-07-03 11:24:54 +02:00
init init: fix false positives in W+X checking 2018-06-21 04:02:57 +09:00
ipc ipc/shm: fix shmat() nil address after round-down when remapping 2018-05-30 07:51:49 +02:00
kernel time: Make sure jiffies_to_msecs() preserves non-zero time periods 2018-07-03 11:24:56 +02:00
lib lib/vsprintf: Remove atomic-unsafe support for %pCr 2018-07-03 11:24:48 +02:00
mm mm/ksm.c: ignore STABLE_FLAG of rmap_item->address in rmap_walk_ksm() 2018-07-03 11:25:03 +02:00
net xprtrdma: Return -ENOBUFS when no pages are available 2018-07-03 11:24:54 +02:00
samples samples/bpf: Partially fixes the bpf.o build 2018-04-26 11:02:12 +02:00
scripts kconfig: Avoid format overflow warning from GCC 8.1 2018-06-11 22:49:18 +02:00
security selinux: KASAN: slab-out-of-bounds in xattr_getsecurity 2018-06-05 11:41:56 +02:00
sound ASoC: cirrus: i2s: Fix {TX|RX}LinCtrlData setup 2018-07-03 11:24:48 +02:00
tools perf vendor events: Add Goldmont Plus V1 event file 2018-07-03 11:25:01 +02:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: arm/arm64: vgic: fix possible spectre-v1 in vgic_mmio_read_apr() 2018-06-21 04:02:49 +09:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
…
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
…
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS dt-bindings: Document mti,mips-cpc binding 2018-03-15 10:54:35 +01:00
Makefile Linux 4.14.52 2018-06-26 08:06:33 +08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.