tmpfs: fix use-after-free of mempolicy object

CVE-2013-1767

BugLink: http://bugs.launchpad.net/bugs/1143815

The tmpfs remount logic preserves filesystem mempolicy if the mpol=M
option is not specified in the remount request.  A new policy can be
specified if mpol=M is given.

Before this patch remounting an mpol bound tmpfs without specifying
mpol= mount option in the remount request would set the filesystem's
mempolicy object to a freed mempolicy object.

To reproduce the problem boot a DEBUG_PAGEALLOC kernel and run:
    # mkdir /tmp/x

    # mount -t tmpfs -o size=100M,mpol=interleave nodev /tmp/x

    # grep /tmp/x /proc/mounts
    nodev /tmp/x tmpfs rw,relatime,size=102400k,mpol=interleave:0-3 0 0

    # mount -o remount,size=200M nodev /tmp/x

    # grep /tmp/x /proc/mounts
    nodev /tmp/x tmpfs rw,relatime,size=204800k,mpol=??? 0 0
        # note ? garbage in mpol=... output above

    # dd if=/dev/zero of=/tmp/x/f count=1
        # panic here

Panic:
    BUG: unable to handle kernel NULL pointer dereference at           (null)
    IP: [<          (null)>]           (null)
    [...]
    Oops: 0010 [#1] SMP DEBUG_PAGEALLOC
    Call Trace:
      mpol_shared_policy_init+0xa5/0x160
      shmem_get_inode+0x209/0x270
      shmem_mknod+0x3e/0xf0
      shmem_create+0x18/0x20
      vfs_create+0xb5/0x130
      do_last+0x9a1/0xea0
      path_openat+0xb3/0x4d0
      do_filp_open+0x42/0xa0
      do_sys_open+0xfe/0x1e0
      compat_sys_open+0x1b/0x20
      cstar_dispatch+0x7/0x1f

Non-debug kernels will not crash immediately because referencing the
dangling mpol will not cause a fault.  Instead the filesystem will
reference a freed mempolicy object, which will cause unpredictable
behavior.

The problem boils down to a dropped mpol reference below if
shmem_parse_options() does not allocate a new mpol:

    config = *sbinfo
    shmem_parse_options(data, &config, true)
    mpol_put(sbinfo->mpol)
    sbinfo->mpol = config.mpol  /* BUG: saves unreferenced mpol */

This patch avoids the crash by not releasing the mempolicy if
shmem_parse_options() doesn't create a new mpol.

How far back does this issue go? I see it in both 2.6.36 and 3.3.  I did
not look back further.

Signed-off-by: Greg Thelen <gthelen@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 5f00110f7273f9ff04ac69a5f85bb535a4fd0987)
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
sunvdc: Fix off-by-one in generic_request().

BugLink: http://bugs.launchpad.net/bugs/1150557

[ Upstream commit f4d9605434c0fd4cc8639bf25cfc043418c52362 ]

The 'operations' bitmap corresponds one-for-one with the operation
codes, no adjustment is necessary.

Reported-by: Mark Kettenis <mark.kettenis@xs4all.nl>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
genirq: Avoid deadlock in spurious handling

BugLink: http://bugs.launchpad.net/bugs/1150557

commit e716efde75267eab919cdb2bef5b2cb77f305326 upstream.

commit 52553ddf(genirq: fix regression in irqfixup, irqpoll)
introduced a potential deadlock by calling the action handler with the
irq descriptor lock held.

Remove the call and let the handling code run even for an interrupt
where only a single action is registered. That matches the goal of
the above commit and avoids the deadlock.

Document the confusing action = desc->action reload in the handling
loop while at it.

Reported-and-tested-by: "Wang, Warner" <warner.wang@hp.com>
Tested-by: Edward Donovan <edward.donovan@numble.net>
Cc: "Wang, Song-Bo (Stoney)" <song-bo.wang@hp.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
KVM: s390: Handle hosts not supporting s390-virtio.

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 55c171a6d90dc0574021f9c836127cfd1a7d2e30 upstream.

Running under a kvm host does not necessarily imply the presence of
a page mapped above the main memory with the virtio information;
however, the code includes a hard coded access to that page.

Instead, check for the presence of the page and exit gracefully
before we hit an addressing exception if it does not exist.

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
workqueue: consider work function when searching for busy work items

BugLink: http://bugs.launchpad.net/bugs/1150557

commit a2c1c57be8d9fd5b716113c8991d3d702eeacf77 upstream.

To avoid executing the same work item concurrenlty, workqueue hashes
currently busy workers according to their current work items and looks
up the the table when it wants to execute a new work item.  If there
already is a worker which is executing the new work item, the new item
is queued to the found worker so that it gets executed only after the
current execution finishes.

Unfortunately, a work item may be freed while being executed and thus
recycled for different purposes.  If it gets recycled for a different
work item and queued while the previous execution is still in
progress, workqueue may make the new work item wait for the old one
although the two aren't really related in any way.

In extreme cases, this false dependency may lead to deadlock although
it's extremely unlikely given that there aren't too many self-freeing
work item users and they usually don't wait for other work items.

To alleviate the problem, record the current work function in each
busy worker and match it together with the work item address in
find_worker_executing_work().  While this isn't complete, it ensures
that unrelated work items don't interact with each other and in the
very unlikely case where a twisted wq user triggers it, it's always
onto itself making the culprit easy to spot.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Andrey Isakov <andy51@gmx.ru>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=51701
[bwh: Backported to 3.2:
 - Adjust context
 - Incorporate earlier logging cleanup in process_one_work() from
   044c782ce3a9 ('workqueue: fix checkpatch issues')]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
v4l: Reset subdev v4l2_dev field to NULL if registration fails

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 317efce991620adc589b3005b9baed433dcb2a56 upstream.

When subdev registration fails the subdev v4l2_dev field is left to a
non-NULL value. Later calls to v4l2_device_unregister_subdev() will
consider the subdev as registered and will module_put() the subdev
module without any matching module_get().
Fix this by setting the subdev v4l2_dev field to NULL in
v4l2_device_register_subdev() when the function fails.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[bwh: Backported to 3.2: adjust context, filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
omap_vout: find_vma() needs ->mmap_sem held

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 55ee64b30a38d688232e5eb2860467dddc493573 upstream.

Walking rbtree while it's modified is a Bad Idea(tm); besides,
the result of find_vma() can be freed just as it's getting returned
to caller.  Fortunately, it's easy to fix - just take ->mmap_sem a bit
earlier (and don't bother with find_vma() at all if virtp >= PAGE_OFFSET -
in that case we don't even look at its result).

While we are at it, what prevents VIDIOC_PREPARE_BUF calling
v4l_prepare_buf() -> (e.g) vb2_ioctl_prepare_buf() -> vb2_prepare_buf() ->
__buf_prepare() -> __qbuf_userptr() -> vb2_vmalloc_get_userptr() -> find_vma(),
AFAICS without having taken ->mmap_sem anywhere in process?  The code flow
is bloody convoluted and depends on a bunch of things done by initialization,
so I certainly might've missed something...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Archit Taneja <archit@ti.com>
Cc: Prabhakar Lad <prabhakar.lad@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
dca: check against empty dca_domains list before unregister provider

BugLink: http://bugs.launchpad.net/bugs/1150557

commit c419fcfd071cf34ba00f9f65282583772d2655e7 upstream.

When providers get blocked unregister_dca_providers() is called ending up
with dca_providers and dca_domain lists emptied. Dca should be prevented from
trying to unregister any provider if dca_domain list is found empty.

Reported-by: Jiang Liu <jiang.liu@huawei.com>
Tested-by: Gaohuai Han <hangaohuai@huawei.com>
Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <djbw@fb.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/eeh: Fix crash when adding a device in a slot with DDW

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 6a040ce72598159a74969a2d01ab0ba5ee6536b3 upstream.

The DDW code uses a eeh_dev struct from the pci_dev. However, this is
not set until eeh_add_device_late is called.

Since pci_bus_add_devices is called before eeh_add_device_late, the PCI
devices are added to the bus, making drivers' probe hooks to be called.
These will call set_dma_mask, which will call the DDW code, which will
require the eeh_dev struct from pci_dev. This would result in a crash,
due to a NULL dereference.

Calling eeh_add_device_late after pci_bus_add_devices would make the
system BUG, because device files shouldn't be added to devices there
were not added to the system. So, a new function is needed to add such
files only after pci_bus_add_devices have been called.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Acked-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: return ENOMEM if sb_getblk() fails

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 860d21e2c585f7ee8a4ecc06f474fdc33c9474f4 upstream.

The only reason for sb_getblk() failing is if it can't allocate the
buffer_head.  So ENOMEM is more appropriate than EIO.  In addition,
make sure that the file system is marked as being inconsistent if
sb_getblk() fails.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
[bwh: Backported to 3.2:
 - Adjust context
 - Drop change to inline.c
 - Call to ext4_ext_check() from ext4_ext_find_extent() is conditional]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
pcmcia/vrc4171: Add missing spinlock init

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 811af9723859884f2f771f3174f3ddedab7c53b5 upstream.

It doesn't seem this spinlock was properly initialized. This bug was
introduced by commit 7a410e8d4d97457c8c381e2de9cdc7bd3306badc.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Purge existing TLB entries in set_pte_at and ptep_set_wrprotect

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 7139bc1579901b53db7e898789e916ee2fb52d78 upstream.

This patch goes a long way toward fixing the minifail bug, and
it  significantly improves the stability of SMP machines such as
the rp3440.  When write  protecting a page for COW, we need to
purge the existing translation.  Otherwise, the COW break
doesn't occur as expected because the TLB may still have a stale entry
which allows writes.

[jejb: fix up checkpatch errors]
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ARM: PXA3xx: program the CSMSADRCFG register

BugLink: http://bugs.launchpad.net/bugs/1150557

commit d107a204154ddd79339203c2deeb7433f0cf6777 upstream.

The Chip Select Configuration Register must be programmed to 0x2 in
order to achieve the correct behavior of the Static Memory Controller.

Without this patch devices wired to DFI and accessed through SMC cannot
be accessed after resume from S2.

Do not rely on the boot loader to program the CSMSADRCFG register by
programming it in the kernel smemc module.

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
USB: option: add and update Alcatel modems

BugLink: http://bugs.launchpad.net/bugs/1150557

commit f8f0302bbcbd1b14655bef29f6996a2152be559d upstream.

Adding three currently unsupported modems based on information
from .inf driver files:

  Diag  VID_1BBB&PID_0052&MI_00
  AGPS  VID_1BBB&PID_0052&MI_01
  VOICE VID_1BBB&PID_0052&MI_02
  AT    VID_1BBB&PID_0052&MI_03
  Modem VID_1BBB&PID_0052&MI_05
  wwan  VID_1BBB&PID_0052&MI_06

  Diag  VID_1BBB&PID_00B6&MI_00
  AT    VID_1BBB&PID_00B6&MI_01
  Modem VID_1BBB&PID_00B6&MI_02
  wwan  VID_1BBB&PID_00B6&MI_03

  Diag  VID_1BBB&PID_00B7&MI_00
  AGPS  VID_1BBB&PID_00B7&MI_01
  VOICE VID_1BBB&PID_00B7&MI_02
  AT    VID_1BBB&PID_00B7&MI_03
  Modem VID_1BBB&PID_00B7&MI_04
  wwan  VID_1BBB&PID_00B7&MI_05

Updating the blacklist info for the X060S_X200 and X220_X500D,
reserving interfaces for a wwan driver, based on

  wwan VID_1BBB&PID_0000&MI_04
  wwan VID_1BBB&PID_0017&MI_06

Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
quota: autoload the quota_v2 module for QFMT_VFS_V1 quota format

BugLink: http://bugs.launchpad.net/bugs/1150557

commit c3ad83d9efdfe6a86efd44945a781f00c879b7b4 upstream.

Otherwise, ext4 file systems with the quota featured enable will get a
very confusing "No such process" error message if the quota code is
built as a module and the quota_v2 module has not been loaded.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ext4: fix possible use-after-free with AIO

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 091e26dfc156aeb3b73bc5c5f277e433ad39331c upstream.

Running AIO is pinning inode in memory using file reference. Once AIO
is completed using aio_complete(), file reference is put and inode can
be freed from memory. So we have to be sure that calling aio_complete()
is the last thing we do with the inode.

Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
s390/kvm: Fix store status for ACRS/FPRS

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 15bc8d8457875f495c59d933b05770ba88d1eacb upstream.

On store status we need to copy the current state of registers
into a save area. Currently we might save stale versions:
The sie state descriptor doesnt have fields for guest ACRS,FPRS,
those registers are simply stored in the host registers. The host
program must copy these away if needed. We do that in vcpu_put/load.

If we now do a store status in KVM code between vcpu_put/load, the
saved values are not up-to-date. Lets collect the ACRS/FPRS before
saving them.

This also fixes some strange problems with hotplug and virtio-ccw,
since the low level machine check handler (on hotplug a machine check
will happen) will revalidate all registers with the content of the
save area.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
[bwh: Backported to 3.2 as done in 3.0 by Jiri Slaby]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Jiri Slaby <jslaby@suse.cz>
staging: comedi: disallow COMEDI_DEVCONFIG on non-board minors

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 754ab5c0e55dd118273ca2c217c4d95e9fbc8259 upstream.

Comedi has two sorts of minor devices:
(a) normal board minor devices in the range 0 to
COMEDI_NUM_BOARD_MINORS-1 inclusive; and
(b) special subdevice minor devices in the range COMEDI_NUM_BOARD_MINORS
upwards that are used to open the same underlying comedi device as the
normal board minor devices, but with non-default read and write
subdevices for asynchronous commands.

The special subdevice minor devices get created when a board supporting
asynchronous commands is attached to a normal board minor device, and
destroyed when the board is detached from the normal board minor device.
One way to attach or detach a board is by using the COMEDI_DEVCONFIG
ioctl.  This should only be used on normal board minors as the special
subdevice minors are too ephemeral.  In particular, the change
introduced in commit 7d3135af399e92cf4c9bbc5f86b6c140aab3b88c ("staging:
comedi: prevent auto-unconfig of manually configured devices") breaks
horribly for special subdevice minor devices.

Since there's no legitimate use for the COMEDI_DEVCONFIG ioctl on a
special subdevice minor device node, disallow it and return -ENOTTY.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
ALSA: usb-audio: fix Roland A-PRO support

BugLink: http://bugs.launchpad.net/bugs/1150557

commit 7da58046482fceb17c4a0d4afefd9507ec56de7f upstream.

The quirk for the Roland/Cakewalk A-PRO keyboards accidentally used the
wrong interface number, which prevented the driver from attaching to the
device.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
x86-32, mm: Rip out x86_32 NUMA remapping code

BugLink: http://bugs.launchpad.net/bugs/1150557

commit f03574f2d5b2d6229dcdf2d322848065f72953c7 upstream.

This code was an optimization for 32-bit NUMA systems.

It has probably been the cause of a number of subtle bugs over
the years, although the conditions to excite them would have
been hard to trigger.  Essentially, we remap part of the kernel
linear mapping area, and then sometimes part of that area gets
freed back in to the bootmem allocator.  If those pages get
used by kernel data structures (say mem_map[] or a dentry),
there's no big deal.  But, if anyone ever tried to use the
linear mapping for these pages _and_ cared about their physical
address, bad things happen.

For instance, say you passed __GFP_ZERO to the page allocator
and then happened to get handed one of these pages, it zero the
remapped page, but it would make a pte to the _old_ page.
There are probably a hundred other ways that it could screw
with things.

We don't need to hang on to performance optimizations for
these old boxes any more.  All my 32-bit NUMA systems are long
dead and buried, and I probably had access to more than most
people.

This code is causing real things to break today:

	https://lkml.org/lkml/2013/1/9/376

I looked in to actually fixing this, but it requires surgery
to way too much brittle code, as well as stuff like
per_cpu_ptr_to_phys().

[ hpa: Cc: this for -stable, since it is a memory corruption issue.
  However, an alternative is to simply mark NUMA as depends BROKEN
  rather than EXPERIMENTAL in the X86_32 subclause... ]

Link: http://lkml.kernel.org/r/20130131005616.1C79F411@kernel.stglabs.ibm.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
[bwh: For 3.2, using the suggested alternative]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>