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Filename Latest commit message Latest commit date
David Hildenbrand 689dacb2b0 device-dax: don't leak kernel memory to user space after unloading kmem
commit 60858c00e5f018eda711a3aa84cf62214ef62d61 upstream.

Assume we have kmem configured and loaded:

  [root@localhost ~]# cat /proc/iomem
  ...
  140000000-33fffffff : Persistent Memory$
    140000000-1481fffff : namespace0.0
    150000000-33fffffff : dax0.0
      150000000-33fffffff : System RAM

Assume we try to unload kmem. This force-unloading will work, even if
memory cannot get removed from the system.

  [root@localhost ~]# rmmod kmem
  [   86.380228] removing memory fails, because memory [0x0000000150000000-0x0000000157ffffff] is onlined
  ...
  [   86.431225] kmem dax0.0: DAX region [mem 0x150000000-0x33fffffff] cannot be hotremoved until the next reboot

Now, we can reconfigure the namespace:

  [root@localhost ~]# ndctl create-namespace --force --reconfig=namespace0.0 --mode=devdax
  [  131.409351] nd_pmem namespace0.0: could not reserve region [mem 0x140000000-0x33fffffff]dax
  [  131.410147] nd_pmem: probe of namespace0.0 failed with error -16namespace0.0 --mode=devdax
  ...

This fails as expected due to the busy memory resource, and the memory
cannot be used.  However, the dax0.0 device is removed, and along its
name.

The name of the memory resource now points at freed memory (name of the
device):

  [root@localhost ~]# cat /proc/iomem
  ...
  140000000-33fffffff : Persistent Memory
    140000000-1481fffff : namespace0.0
    150000000-33fffffff : �_�^7_��/_��wR��WQ���^��� ...
    150000000-33fffffff : System RAM

We have to make sure to duplicate the string.  While at it, remove the
superfluous setting of the name and fixup a stale comment.

Fixes: 9f960da72b ("device-dax: "Hotremove" persistent memory that is used like normal RAM")
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@vger.kernel.org>	[5.3]
Link: http://lkml.kernel.org/r/20200508084217.9160-2-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-27 17:46:48 +02:00
arch s390/kaslr: add support for R_390_JMP_SLOT relocation type 2020-05-27 17:46:47 +02:00
block iocost: protect iocg->abs_vdebt with iocg->waitq.lock 2020-05-14 07:58:27 +02:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto gcc-10: avoid shadowing standard library 'free()' in crypto 2020-05-20 08:20:29 +02:00
Documentation USB: hub: Revert commit bd0e6c9614 ("usb: hub: try old enumeration scheme first for high speed devices") 2020-04-29 16:33:14 +02:00
drivers device-dax: don't leak kernel memory to user space after unloading kmem 2020-05-27 17:46:48 +02:00
fs Revert "gfs2: Don't demote a glock until its revokes are written" 2020-05-27 17:46:44 +02:00
include bpf: Avoid setting bpf insns pages read-only when prog is jited 2020-05-27 17:46:44 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel Stop the ad-hoc games with -Wno-maybe-initialized 2020-05-20 08:20:28 +02:00
lib vsprintf: don't obfuscate NULL and error pointers 2020-05-27 17:46:43 +02:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm shmem: fix possible deadlocks on shmlock_user_lock 2020-05-20 08:20:03 +02:00
net bpf: Fix sk_psock refcnt leak when receiving message 2020-05-20 08:20:39 +02:00
samples vmalloc: fix remap_vmalloc_range() bounds checks 2020-04-29 16:33:14 +02:00
scripts kbuild: Remove debug info from kallsyms linking 2020-05-27 17:46:44 +02:00
security apparmor: Fix aa_label refcnt leak in policy_update 2020-05-27 17:46:42 +02:00
sound ALSA: hda/realtek - Add more fixup entries for Clevo machines 2020-05-27 17:46:40 +02:00
tools KVM: selftests: Fix build for evmcs.h 2020-05-27 17:46:36 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: arm: vgic: Synchronize the whole guest on GIC{D,R}_I{S,C}ACTIVER read 2020-05-20 08:20:04 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 17:22:19 +01:00
Makefile kbuild: avoid concurrency issue in parallel building dtbs and dtbs_check 2020-05-27 17:46:23 +02:00
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.