The sclp_ctl_ioctl_sccb function uses two copy_from_user calls to
retrieve the sclp request from user space. The first copy_from_user
fetches the length of the request which is stored in the first two
bytes of the request. The second copy_from_user gets the complete
sclp request, but this copies the length field a second time.
A malicious user may have changed the length in the meantime.

Reported-by: Pengfei Wang <wpengfeinudt@gmail.com>
Reviewed-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

dcssblk_remove_store() holds the dcssblk_devices_sem semaphore while
calling device_unregister(), which in turn tries to acquire the kernfs
kn->dev_map rwsem for the device sysfs subtree. The same rwsem is also
acquired when using the per-device sysfs attributes in the device sub-tree,
and the attribute handlers then also acquire the dcssblk_devices_sem.

This can lead to a deadlock when removing a DCSS while concurrently
reading from / writing to one of its sysfs attributes. The following
lockdep warning hinted towards the issue (CPU0 = dcssblk_remove_store,
CPU1 = dcssblk_shared_store):

[   76.496047]  Possible unsafe locking scenario:

[   76.496054]        CPU0                    CPU1
[   76.496059]        ----                    ----
[   76.496087]   lock(&dcssblk_devices_sem);
[   76.496090]                                lock(s_active#175);
[   76.496106]                                lock(&dcssblk_devices_sem);
[   76.496110]   lock(s_active#175);
[   76.496115]
 *** DEADLOCK ***

Fix this by releasing the dcssblk_devices_sem semaphore, which only
protects internal DCSS data, before calling device_unregister().

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

When we refuse a non REQ_TYPE_FS request in the build request function
we already hold the queue lock. Thus we must not call blk_end_request_all
but __blk_end_request_all.

Reported-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Fixes: de9587a ('s390/scm_blk: fix endless loop for requests != REQ_TYPE_FS')
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Pull s390 fixes from Martin Schwidefsky:
 - A proper fix for the locking issue in the dasd driver
 - Wire up the new preadv2 nad pwritev2 system calls
 - Add the mark_rodata_ro function and set DEBUG_RODATA=y
 - A few more bug fixes.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: wire up preadv2/pwritev2 syscalls
  s390/pci: PCI function group 0 is valid for clp_query_pci_fn
  s390/crypto: provide correct file mode at device register.
  s390/mm: handle PTE-mapped tail pages in fast gup
  s390: add DEBUG_RODATA support
  s390: disable postinit-readonly for now
  s390/dasd: reorder lcu and device lock
  s390/cpum_sf: Fix cpu hotplug notifier transitions
  s390/cpum_cf: Fix missing cpu hotplug notifier transition

Pull virtio/vhost updates from Michael Tsirkin:
 "New features, performance improvements, cleanups:

   - basic polling support for vhost
   - rework virtio to optionally use DMA API, fixing it on Xen
   - balloon stats gained a new entry
   - using the new napi_alloc_skb speeds up virtio net
   - virtio blk stats can now be read while another VCPU is busy
     inflating or deflating the balloon

  plus misc cleanups in various places"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio_net: replace netdev_alloc_skb_ip_align() with napi_alloc_skb()
  vhost_net: basic polling support
  vhost: introduce vhost_vq_avail_empty()
  vhost: introduce vhost_has_work()
  virtio_balloon: Allow to resize and update the balloon stats in parallel
  virtio_balloon: Use a workqueue instead of "vballoon" kthread
  virtio/s390: size of SET_IND payload
  virtio/s390: use dev_to_virtio
  vhost: rename vhost_init_used()
  vhost: rename cross-endian helpers
  virtio_blk: VIRTIO_BLK_F_WCE->VIRTIO_BLK_F_FLUSH
  vring: Use the DMA API on Xen
  virtio_pci: Use the DMA API if enabled
  virtio_mmio: Use the DMA API if enabled
  virtio: Add improved queue allocation API
  virtio_ring: Support DMA APIs
  vring: Introduce vring_use_dma_api()
  s390/dma: Allow per device dma ops
  alpha/dma: use common noop dma ops
  dma: Provide simple noop dma ops

Pull tty/serial updates from Greg KH:
 "Here's the big tty/serial driver pull request for 4.6-rc1.

  Lots of changes in here, Peter has been on a tear again, with lots of
  refactoring and bugs fixes, many thanks to the great work he has been
  doing.  Lots of driver updates and fixes as well, full details in the
  shortlog.

  All have been in linux-next for a while with no reported issues"

* tag 'tty-4.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (220 commits)
  serial: 8250: describe CONFIG_SERIAL_8250_RSA
  serial: samsung: optimize UART rx fifo access routine
  serial: pl011: add mark/space parity support
  serial: sa1100: make sa1100_register_uart_fns a function
  tty: serial: 8250: add MOXA Smartio MUE boards support
  serial: 8250: convert drivers to use up_to_u8250p()
  serial: 8250/mediatek: fix building with SERIAL_8250=m
  serial: 8250/ingenic: fix building with SERIAL_8250=m
  serial: 8250/uniphier: fix modular build
  Revert "drivers/tty/serial: make 8250/8250_ingenic.c explicitly non-modular"
  Revert "drivers/tty/serial: make 8250/8250_mtk.c explicitly non-modular"
  serial: mvebu-uart: initial support for Armada-3700 serial port
  serial: mctrl_gpio: Add missing module license
  serial: ifx6x60: avoid uninitialized variable use
  tty/serial: at91: fix bad offset for UART timeout register
  tty/serial: at91: restore dynamic driver binding
  serial: 8250: Add hardware dependency to RT288X option
  TTY, devpts: document pty count limiting
  tty: goldfish: support platform_device with id -1
  drivers: tty: goldfish: Add device tree bindings
  ...

Reorder lcu and device lock to get rid of the error-prone trylock
mechanism.

The locking order is lcu lock -> device lock.
This protects against changes to the lcu device lists and enables us
to iterate over the devices, take the cdev lock and make changes to
the device structures.

The complicated part is the summary unit check handler that gets an
interrupt on one device of the lcu that leads to structural changes of
the whole lcu itself. This work needs to be done even if devices on
the lcu disappear. So a device independent worker is used.
The old approach tried to update some lcu structures and set up the
lcu worker in the interrupt context with the device lock held.
But this forced the lock order "cdev lock -> lcu lock" that made it
hard to have the lcu lock held and iterate over all devices and change
them.

The new approach is to schedule a device specific worker that gets
out of the interrupt context and rid of the device lock for summary
unit checks. This worker is able to take the lcu lock and schedule the
lcu worker that updates all devices. The time between interrupt and
worker execution is no problem because the devices in the lcu reject
all I/O in this time with an appropriate error. The dasd driver can
deal with this situation and re-drive the I/O later on.

Signed-off-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Pull s390 updates from Martin Schwidefsky:

 - Add the CPU id for the new z13s machine

 - Add a s390 specific XOR template for RAID-5 checksumming based on the
   XC instruction.  Remove all other alternatives, XC is always faster

 - The merge of our four different stack tracers into a single one

 - Tidy up the code related to page tables, several large inline
   functions are now out-of-line.  Bloat-o-meter reports ~11K text size
   reduction

 - A binary interface for the priviledged CLP instruction to retrieve
   the hardware view of the installed PCI functions

 - Improvements for the dasd format code

 - Bug fixes and cleanups

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (31 commits)
  s390/pci: enforce fmb page boundary rule
  s390: fix floating pointer register corruption (again)
  s390/cpumf: add missing lpp magic initialization
  s390: Fix misspellings in comments
  s390/mm: split arch/s390/mm/pgtable.c
  s390/mm: uninline pmdp_xxx functions from pgtable.h
  s390/mm: uninline ptep_xxx functions from pgtable.h
  s390/pci: add ioctl interface for CLP
  s390: Use pr_warn instead of pr_warning
  s390/dasd: remove casts to dasd_*_private
  s390/dasd: Refactor dasd format functions
  s390/dasd: Simplify code in format logic
  s390/dasd: Improve dasd format code
  s390/percpu: remove this_cpu_cmpxchg_double_4
  s390/cpumf: Improve guest detection heuristics
  s390/fault: merge report_user_fault implementations
  s390/dis: use correct escape sequence for '%' character
  s390/kvm: simplify set_guest_storage_key
  s390/oprofile: add z13/z13s model numbers
  s390: add z13s model number to z13 elf platform
  ...

Convert the uses of pr_warning to pr_warn so there are fewer
uses of the old pr_warning.

Miscellanea:

o Align arguments
o Coalesce formats

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Convert dasd_device.private to be a void pointer to get
rid of a lot of explicit casts.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>