Currently, panic() and crash_kexec() can be called at the same time.
For example (x86 case):

CPU 0:
  oops_end()
    crash_kexec()
      mutex_trylock() // acquired
        nmi_shootdown_cpus() // stop other CPUs

CPU 1:
  panic()
    crash_kexec()
      mutex_trylock() // failed to acquire
    smp_send_stop() // stop other CPUs
    infinite loop

If CPU 1 calls smp_send_stop() before nmi_shootdown_cpus(), kdump
fails.

In another case:

CPU 0:
  oops_end()
    crash_kexec()
      mutex_trylock() // acquired
        <NMI>
        io_check_error()
          panic()
            crash_kexec()
              mutex_trylock() // failed to acquire
            infinite loop

Clearly, this is an undesirable result.

To fix this problem, this patch changes crash_kexec() to exclude others
by using the panic_cpu atomic.
Signed-off-by: NHidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: kexec@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Minfei Huang <mnfhuang@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/20151210014630.25437.94161.stgit@softrsSigned-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Currently, kdump_nmi_shootdown_cpus(), a subroutine of crash_kexec(),
sends an NMI IPI to CPUs which haven't called panic() to stop them,
save their register information and do some cleanups for crash dumping.
However, if such a CPU is infinitely looping in NMI context, we fail to
save its register information into the crash dump.

For example, this can happen when unknown NMIs are broadcast to all
CPUs as follows:

  CPU 0                             CPU 1
  ===========================       ==========================
  receive an unknown NMI
  unknown_nmi_error()
    panic()                         receive an unknown NMI
      spin_trylock(&panic_lock)     unknown_nmi_error()
      crash_kexec()                   panic()
                                        spin_trylock(&panic_lock)
                                        panic_smp_self_stop()
                                          infinite loop
        kdump_nmi_shootdown_cpus()
          issue NMI IPI -----------> blocked until IRET
                                          infinite loop...

Here, since CPU 1 is in NMI context, the second NMI from CPU 0 is
blocked until CPU 1 executes IRET. However, CPU 1 never executes IRET,
so the NMI is not handled and the callback function to save registers is
never called.

In practice, this can happen on some servers which broadcast NMIs to all
CPUs when the NMI button is pushed.

To save registers in this case, we need to:

  a) Return from NMI handler instead of looping infinitely
  or
  b) Call the callback function directly from the infinite loop

Inherently, a) is risky because NMI is also used to prevent corrupted
data from being propagated to devices.  So, we chose b).

This patch does the following:

1. Move the infinite looping of CPUs which haven't called panic() in NMI
   context (actually done by panic_smp_self_stop()) outside of panic() to
   enable us to refer pt_regs. Please note that panic_smp_self_stop() is
   still used for normal context.

2. Call a callback of kdump_nmi_shootdown_cpus() directly to save
   registers and do some cleanups after setting waiting_for_crash_ipi which
   is used for counting down the number of CPUs which handled the callback
Signed-off-by: NHidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Gobinda Charan Maji <gobinda.cemk07@gmail.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Javi Merino <javi.merino@arm.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: kexec@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: lkml <linux-kernel@vger.kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Stefan Lippers-Hollmann <s.l-h@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Link: http://lkml.kernel.org/r/20151210014628.25437.75256.stgit@softrs
[ Cleanup comments, fixup formatting. ]
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

If panic on NMI happens just after panic() on the same CPU, panic() is
recursively called. Kernel stalls, as a result, after failing to acquire
panic_lock.

To avoid this problem, don't call panic() in NMI context if we've
already entered panic().

For that, introduce nmi_panic() macro to reduce code duplication. In
the case of panic on NMI, don't return from NMI handlers if another CPU
already panicked.
Signed-off-by: NHidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Gobinda Charan Maji <gobinda.cemk07@gmail.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Javi Merino <javi.merino@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: kexec@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: lkml <linux-kernel@vger.kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Link: http://lkml.kernel.org/r/20151210014626.25437.13302.stgit@softrs
[ Cleanup comments, fixup formatting. ]
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Pull in update changes so we can apply conflicting patches

Pull power management fixes from Rafael Wysocki:
 "These fix a potential regression introduced during the 4.3 cycle
  (generic power domains framework), a nasty bug that has been present
  forever (power capping RAPL driver), a build issue (Tegra cpufreq
  driver) and a minor ugliness introduced recently (intel_pstate).

  Specifics:

   - Fix a potential regression in the generic power domains framework
     introduced during the 4.3 development cycle that may lead to
     spurious failures of system suspend in certain situations (Ulf
     Hansson).

   - Fix a problem in the power capping RAPL (Running Average Power
     Limits) driver that causes it to initialize successfully on some
     systems where it is not supposed to do that which is due to an
     incorrect check in an initialization routine (Prarit Bhargava).

   - Fix a build problem in the cpufreq Tegra driver that depends on the
     regulator framework, but that dependency is not reflected in
     Kconfig (Arnd Bergmann).

   - Fix a recent mistake in the intel_pstate driver where a numeric
     constant is used directly instead of a symbol defined specifically
     for the case in question (Prarit Bhargava)"

* tag 'pm+acpi-4.4-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  powercap / RAPL: fix BIOS lock check
  cpufreq: intel_pstate: Minor cleanup for FRAC_BITS
  cpufreq: tegra: add regulator dependency for T124
  PM / Domains: Allow runtime PM callbacks to be re-used during system PM

Pull SCSI fixes from James Bottomley:
 "Three fixes this time, two in SES picked up by KASAN for various types
  of buffer overrun.  The first is a USB array which returns page 8
  whatever is asked for and causes us to overrun with incorrect data
  format assumptions and the second is an invalid iteration of page 10
  (the additional information page).

  The final fix is a reversion of a NULL deref fix which caused
  suspend/resume not to be called in pairs leading to incorrect device
  operation (Jens has queued a more proper fix for the problem in
  block)"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  ses: fix additional element traversal bug
  Revert "SCSI: Fix NULL pointer dereference in runtime PM"
  ses: Fix problems with simple enclosures

Pull media fixes from Mauro Carvalho Chehab.

* tag 'media/v4.4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
  [media] airspy: increase USB control message buffer size
  [media] hackrf: move RF gain ctrl enable behind module parameter
  [media] hackrf: fix possible null ptr on debug printing
  [media] Revert "[media] ivtv: avoid going past input/audio array"

Pull btrfs fixes from Chris Mason:
 "A couple of small fixes"

* 'for-linus-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: check prepare_uptodate_page() error code earlier
  Btrfs: check for empty bitmap list in setup_cluster_bitmaps
  btrfs: fix misleading warning when space cache failed to load
  Btrfs: fix transaction handle leak in balance
  Btrfs: fix unprotected list move from unused_bgs to deleted_bgs list

Merge misc fixes from Andrew Morton:
 "Three patches"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  include/linux/mmdebug.h: should include linux/bug.h
  mm/zswap: change incorrect strncmp use to strcmp
  proc: fix -ESRCH error when writing to /proc/$pid/coredump_filter

mmdebug.h uses BUILD_BUG_ON_INVALID(), assuming someone else included
linux/bug.h.  Include it ourselves.

This saves build-failures such as:

  arch/arm64/include/asm/pgtable.h: In function 'set_pte_at':
  arch/arm64/include/asm/pgtable.h:281:3: error: implicit declaration of function 'BUILD_BUG_ON_INVALID' [-Werror=implicit-function-declaration]
   VM_WARN_ONCE(!pte_young(pte),

Fixes: 02602a18 ("bug: completely remove code generated by disabled VM_BUG_ON()")
Signed-off-by: NJames Morse <james.morse@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change the use of strncmp in zswap_pool_find_get() to strcmp.

The use of strncmp is no longer correct, now that zswap_zpool_type is
not an array; sizeof() will return the size of a pointer, which isn't
the right length to compare.  We don't need to use strncmp anyway,
because the existing params and the passed in params are all guaranteed
to be null terminated, so strcmp should be used.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Reported-by: NWeijie Yang <weijie.yang@samsung.com>
Cc: Seth Jennings <sjennings@variantweb.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Writing to /proc/$pid/coredump_filter always returns -ESRCH because commit
774636e1 ("proc: convert to kstrto*()/kstrto*_from_user()") removed
the setting of ret after the get_proc_task call and incorrectly left it as
-ESRCH.  Instead, return 0 when successful.

Example breakage:

  echo 0 > /proc/self/coredump_filter
  bash: echo: write error: No such process

Fixes: 774636e1 ("proc: convert to kstrto*()/kstrto*_from_user()")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-by: NKees Cook <keescook@chromium.org>
Cc: <stable@vger.kernel.org> [4.3+]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Merge tag 'hwmon-for-linus-v4.4-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging

Pull hwmon fixes from Guenter Roeck:

 - Select CONFIG_BITREVERSE for sht15 driver to avoid build failure if
   it is not configured.

 - Force wait for conversion time for the first valid data in tmp102
   driver to avoid reporting erroneous data to the thermal subsystem.

* tag 'hwmon-for-linus-v4.4-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (sht15) Select CONFIG_BITREVERSE
  hwmon: (tmp102) Force wait for conversion time for the first valid data

Pull IOMMU fixes from Joerg Roedel:
 "Two similar fixes for the Intel and AMD IOMMU drivers to add proper
  access checks before calling handle_mm_fault"

* tag 'iommu-fixes-v4.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/vt-d: Do access checks before calling handle_mm_fault()
  iommu/amd: Do proper access checking before calling handle_mm_fault()

Pull xen bug fixes from David Vrabel:
 - XSA-155 security fixes to backend drivers.
 - XSA-157 security fixes to pciback.

* tag 'for-linus-4.4-rc5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen-pciback: fix up cleanup path when alloc fails
  xen/pciback: Don't allow MSI-X ops if PCI_COMMAND_MEMORY is not set.
  xen/pciback: For XEN_PCI_OP_disable_msi[|x] only disable if device has MSI(X) enabled.
  xen/pciback: Do not install an IRQ handler for MSI interrupts.
  xen/pciback: Return error on XEN_PCI_OP_enable_msix when device has MSI or MSI-X enabled
  xen/pciback: Return error on XEN_PCI_OP_enable_msi when device has MSI or MSI-X enabled
  xen/pciback: Save xen_pci_op commands before processing it
  xen-scsiback: safely copy requests
  xen-blkback: read from indirect descriptors only once
  xen-blkback: only read request operation from shared ring once
  xen-netback: use RING_COPY_REQUEST() throughout
  xen-netback: don't use last request to determine minimum Tx credit
  xen: Add RING_COPY_REQUEST()
  xen/x86/pvh: Use HVM's flush_tlb_others op
  xen: Resume PMU from non-atomic context
  xen/events/fifo: Consume unprocessed events when a CPU dies

Pull ARC architecture fixes from Vineet Gupta:
 "Fixes for:

 - perf interrupts on SMP: Not enabled (at boot) and disabled (at runtime)
 - stack unwinder regression (for modules, ignoring dwarf3)
 - nsim hosed for non default kernel link base builds"

* tag 'arc-fixes-for-4.4-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: smp: Rename platform hook @init_cpu_smp -> @init_per_cpu
  ARC: rename smp operation init_irq_cpu() to init_per_cpu()
  ARC: dw2 unwind: Ignore CIE version !=1 gracefully instead of bailing
  ARC: dw2 unwind: Reinstante unwinding out of modules
  ARC: [plat-sim] unbork non default CONFIG_LINUX_LINK_BASE
  ARC: intc: Document arc_request_percpu_irq() better
  ARCv2: perf: Ensure perf intr gets enabled on all cores
  ARC: intc: No need to clear IRQ_NOAUTOEN
  ARCv2: intc: Fix random perf irq disabling in SMP setup
  ARC: [axs10x] cap ethernet phy to 100 Mbit/sec

Pull sound fixes from Takashi Iwai:
 "As usual in rc6, this update contains only a few HD-audio and
  USB-audio device-specific quirks: yet another Thinkpad noise fixes,
  Dell headphone mic fixes, and AudioQuest DragonFly fixes"

* tag 'sound-4.4-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - Add a fixup for Thinkpad X1 Carbon 2nd
  ALSA: hda - Set codec to D3 at reboot/shutdown on Thinkpads
  ALSA: hda - Apply click noise workaround for Thinkpads generically
  ALSA: hda - Fix headphone mic input on a few Dell ALC293 machines
  ALSA: usb-audio: Add sample rate inquiry quirk for AudioQuest DragonFly
  ALSA: usb-audio: Add a more accurate volume quirk for AudioQuest DragonFly

Pull MTD fixes from Brian Norris:
 "I was holding out on this pull request for a bit, since there are a
  few other small issues being discussed that look like 4.4-rc
  regressions.  Hopefully I can get those stabilized soon, but these are
  ready at any rate:

   - A little bit of a last-minute change for the device tree "fixed
     partition" binding.  This is needed because we might want to reuse
     the 'partitions' subnode for other sorts of partitioning
     descriptions -- e.g., for describing which on-flash partition
     format(s) might be used on the system.

   - Also tone down a warning message, since it is probably going to
     show up on a lot of systems where it should just be ignored"

* tag 'for-linus-20151217' of git://git.infradead.org/linux-mtd:
  doc: dt: mtd: partitions: add compatible property to "partitions" node
  mtd: ofpart: don't complain about missing 'partitions' node too loudly

Driver requested device firmware version string during probe using
only 24 byte long buffer. That buffer is too small for newer firmware
versions, which causes device firmware hang - device stops responding
to any commands after that. Increase buffer size to 128 which should
be enough for any current and future version strings.

Link: https://github.com/airspy/host/issues/27

Cc: <stable@vger.kernel.org> # 3.17+
Reported-by: NBenjamin Vernoux <bvernoux@gmail.com>
Signed-off-by: NAntti Palosaari <crope@iki.fi>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Used Avago MGA-81563 RF amplifier could be destroyed pretty easily
with too strong signal or transmitting to bad antenna.
Add module parameter 'enable_rf_gain_ctrl' which allows enabling
RF gain control - otherwise, default without the module parameter,
RF gain control is set to 'grabbed' state which prevents setting
value to the control.
Signed-off-by: NAntti Palosaari <crope@iki.fi>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/hackrf/hackrf.c:1533 hackrf_probe()
error: we previously assumed 'dev' could be null (see line 1366)
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAntti Palosaari <crope@iki.fi>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

This patch broke ivtv logic, as reported at
 https://bugzilla.redhat.com/show_bug.cgi?id=1278942

This reverts commit 09290cc8.

Cc: stable@vger.kernel.org # for v4.1 and upper
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

When allocating a pciback device fails, clear the private
field. This could lead to an use-after free, however
the 'really_probe' takes care of setting
dev_set_drvdata(dev, NULL) in its failure path (which we would
exercise if the ->probe function failed), so we we
are OK. However lets be defensive as the code can change.

Going forward we should clean up the pci_set_drvdata(dev, NULL)
in the various code-base. That will be for another day.
Reviewed-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Reported-by: NJonathan Creekmore <jonathan.creekmore@gmail.com>
Signed-off-by: NDoug Goldstein <cardoe@cardoe.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

If CONFIG_BITREVERSE is not built-in, the sht15 driver fails to link:

drivers/built-in.o: In function `sht15_crc8':
drivers/hwmon/sht15.c:195: undefined reference to `byte_rev_table'

This adds a Kconfig 'select' statement, like all other users of
bitrev.h have it.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Fixes: 33836ee9 ("hwmon:change sht15_reverse()")
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>

commit f598282f ("PCI: Fix the NIU MSI-X problem in a better way")
teaches us that dealing with MSI-X can be troublesome.

Further checks in the MSI-X architecture shows that if the
PCI_COMMAND_MEMORY bit is turned of in the PCI_COMMAND we
may not be able to access the BAR (since they are memory regions).

Since the MSI-X tables are located in there.. that can lead
to us causing PCIe errors. Inhibit us performing any
operation on the MSI-X unless the MEMORY bit is set.

Note that Xen hypervisor with:
"x86/MSI-X: access MSI-X table only after having enabled MSI-X"
will return:
xen_pciback: 0000:0a:00.1: error -6 enabling MSI-X for guest 3!

When the generic MSI code tries to setup the PIRQ without
MEMORY bit set. Which means with later versions of Xen
(4.6) this patch is not neccessary.

This is part of XSA-157

CC: stable@vger.kernel.org
Reviewed-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Otherwise just continue on, returning the same values as
previously (return of 0, and op->result has the PIRQ value).

This does not change the behavior of XEN_PCI_OP_disable_msi[|x].

The pci_disable_msi or pci_disable_msix have the checks for
msi_enabled or msix_enabled so they will error out immediately.

However the guest can still call these operations and cause
us to disable the 'ack_intr'. That means the backend IRQ handler
for the legacy interrupt will not respond to interrupts anymore.

This will lead to (if the device is causing an interrupt storm)
for the Linux generic code to disable the interrupt line.

Naturally this will only happen if the device in question
is plugged in on the motherboard on shared level interrupt GSI.

This is part of XSA-157

CC: stable@vger.kernel.org
Reviewed-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Otherwise an guest can subvert the generic MSI code to trigger
an BUG_ON condition during MSI interrupt freeing:

 for (i = 0; i < entry->nvec_used; i++)
        BUG_ON(irq_has_action(entry->irq + i));

Xen PCI backed installs an IRQ handler (request_irq) for
the dev->irq whenever the guest writes PCI_COMMAND_MEMORY
(or PCI_COMMAND_IO) to the PCI_COMMAND register. This is
done in case the device has legacy interrupts the GSI line
is shared by the backend devices.

To subvert the backend the guest needs to make the backend
to change the dev->irq from the GSI to the MSI interrupt line,
make the backend allocate an interrupt handler, and then command
the backend to free the MSI interrupt and hit the BUG_ON.

Since the backend only calls 'request_irq' when the guest
writes to the PCI_COMMAND register the guest needs to call
XEN_PCI_OP_enable_msi before any other operation. This will
cause the generic MSI code to setup an MSI entry and
populate dev->irq with the new PIRQ value.

Then the guest can write to PCI_COMMAND PCI_COMMAND_MEMORY
and cause the backend to setup an IRQ handler for dev->irq
(which instead of the GSI value has the MSI pirq). See
'xen_pcibk_control_isr'.

Then the guest disables the MSI: XEN_PCI_OP_disable_msi
which ends up triggering the BUG_ON condition in 'free_msi_irqs'
as there is an IRQ handler for the entry->irq (dev->irq).

Note that this cannot be done using MSI-X as the generic
code does not over-write dev->irq with the MSI-X PIRQ values.

The patch inhibits setting up the IRQ handler if MSI or
MSI-X (for symmetry reasons) code had been called successfully.

P.S.
Xen PCIBack when it sets up the device for the guest consumption
ends up writting 0 to the PCI_COMMAND (see xen_pcibk_reset_device).
XSA-120 addendum patch removed that - however when upstreaming said
addendum we found that it caused issues with qemu upstream. That
has now been fixed in qemu upstream.

This is part of XSA-157

CC: stable@vger.kernel.org
Reviewed-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The guest sequence of:

  a) XEN_PCI_OP_enable_msix
  b) XEN_PCI_OP_enable_msix

results in hitting an NULL pointer due to using freed pointers.

The device passed in the guest MUST have MSI-X capability.

The a) constructs and SysFS representation of MSI and MSI groups.
The b) adds a second set of them but adding in to SysFS fails (duplicate entry).
'populate_msi_sysfs' frees the newly allocated msi_irq_groups (note that
in a) pdev->msi_irq_groups is still set) and also free's ALL of the
MSI-X entries of the device (the ones allocated in step a) and b)).

The unwind code: 'free_msi_irqs' deletes all the entries and tries to
delete the pdev->msi_irq_groups (which hasn't been set to NULL).
However the pointers in the SysFS are already freed and we hit an
NULL pointer further on when 'strlen' is attempted on a freed pointer.

The patch adds a simple check in the XEN_PCI_OP_enable_msix to guard
against that. The check for msi_enabled is not stricly neccessary.

This is part of XSA-157

CC: stable@vger.kernel.org
Reviewed-by: NDavid Vrabel <david.vrabel@citrix.com>
Reviewed-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The guest sequence of:

 a) XEN_PCI_OP_enable_msi
 b) XEN_PCI_OP_enable_msi
 c) XEN_PCI_OP_disable_msi

results in hitting an BUG_ON condition in the msi.c code.

The MSI code uses an dev->msi_list to which it adds MSI entries.
Under the above conditions an BUG_ON() can be hit. The device
passed in the guest MUST have MSI capability.

The a) adds the entry to the dev->msi_list and sets msi_enabled.
The b) adds a second entry but adding in to SysFS fails (duplicate entry)
and deletes all of the entries from msi_list and returns (with msi_enabled
is still set).  c) pci_disable_msi passes the msi_enabled checks and hits:

BUG_ON(list_empty(dev_to_msi_list(&dev->dev)));

and blows up.

The patch adds a simple check in the XEN_PCI_OP_enable_msi to guard
against that. The check for msix_enabled is not stricly neccessary.

This is part of XSA-157.

CC: stable@vger.kernel.org
Reviewed-by: NDavid Vrabel <david.vrabel@citrix.com>
Reviewed-by: NJan Beulich <jbeulich@suse.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Double fetch vulnerabilities that happen when a variable is
fetched twice from shared memory but a security check is only
performed the first time.

The xen_pcibk_do_op function performs a switch statements on the op->cmd
value which is stored in shared memory. Interestingly this can result
in a double fetch vulnerability depending on the performed compiler
optimization.

This patch fixes it by saving the xen_pci_op command before
processing it. We also use 'barrier' to make sure that the
compiler does not perform any optimization.

This is part of XSA155.

CC: stable@vger.kernel.org
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NJan Beulich <JBeulich@suse.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The copy of the ring request was lacking a following barrier(),
potentially allowing the compiler to optimize the copy away.

Use RING_COPY_REQUEST() to ensure the request is copied to local
memory.

This is part of XSA155.

CC: stable@vger.kernel.org
Reviewed-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Since indirect descriptors are in memory shared with the frontend, the
frontend could alter the first_sect and last_sect values after they have
been validated but before they are recorded in the request.  This may
result in I/O requests that overflow the foreign page, possibly
overwriting local pages when the I/O request is executed.

When parsing indirect descriptors, only read first_sect and last_sect
once.

This is part of XSA155.

CC: stable@vger.kernel.org
Signed-off-by: NRoger Pau Monné <roger.pau@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

A compiler may load a switch statement value multiple times, which could
be bad when the value is in memory shared with the frontend.

When converting a non-native request to a native one, ensure that
src->operation is only loaded once by using READ_ONCE().

This is part of XSA155.

CC: stable@vger.kernel.org
Signed-off-by: NRoger Pau Monné <roger.pau@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Instead of open-coding memcpy()s and directly accessing Tx and Rx
requests, use the new RING_COPY_REQUEST() that ensures the local copy
is correct.

This is more than is strictly necessary for guest Rx requests since
only the id and gref fields are used and it is harmless if the
frontend modifies these.

This is part of XSA155.

CC: stable@vger.kernel.org
Reviewed-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

The last from guest transmitted request gives no indication about the
minimum amount of credit that the guest might need to send a packet
since the last packet might have been a small one.

Instead allow for the worst case 128 KiB packet.

This is part of XSA155.

CC: stable@vger.kernel.org
Reviewed-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Using RING_GET_REQUEST() on a shared ring is easy to use incorrectly
(i.e., by not considering that the other end may alter the data in the
shared ring while it is being inspected).  Safe usage of a request
generally requires taking a local copy.

Provide a RING_COPY_REQUEST() macro to use instead of
RING_GET_REQUEST() and an open-coded memcpy().  This takes care of
ensuring that the copy is done correctly regardless of any possible
compiler optimizations.

Use a volatile source to prevent the compiler from reordering or
omitting the copy.

This is part of XSA155.

CC: stable@vger.kernel.org
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Pull networking fixes from David Miller:

 1) Fix uninitialized variable warnings in nfnetlink_queue, a lot of
    people reported this...  From Arnd Bergmann.

 2) Don't init mutex twice in i40e driver, from Jesse Brandeburg.

 3) Fix spurious EBUSY in rhashtable, from Herbert Xu.

 4) Missing DMA unmaps in mvpp2 driver, from Marcin Wojtas.

 5) Fix race with work structure access in pppoe driver causing
    corruptions, from Guillaume Nault.

 6) Fix OOPS due to sh_eth_rx() not checking whether netdev_alloc_skb()
    actually succeeded or not, from Sergei Shtylyov.

 7) Don't lose flags when settifn IFA_F_OPTIMISTIC in ipv6 code, from
    Bjørn Mork.

 8) VXLAN_HD_RCO defined incorrectly, fix from Jiri Benc.

 9) Fix clock source used for cookies in SCTP, from Marcelo Ricardo
    Leitner.

10) aurora driver needs HAS_DMA dependency, from Geert Uytterhoeven.

11) ndo_fill_metadata_dst op of vxlan has to handle ipv6 tunneling
    properly as well, from Jiri Benc.

12) Handle request sockets properly in xfrm layer, from Eric Dumazet.

13) Double stats update in ipv6 geneve transmit path, fix from Pravin B
    Shelar.

14) sk->sk_policy[] needs RCU protection, and as a result
    xfrm_policy_destroy() needs to free policies using an RCU grace
    period, from Eric Dumazet.

15) SCTP needs to clone ipv6 tx options in order to avoid use after
    free, from Eric Dumazet.

16) Missing kbuild export if ila.h, from Stephen Hemminger.

17) Missing mdiobus_alloc() return value checking in mdio-mux.c, from
    Tobias Klauser.

18) Validate protocol value range in ->create() methods, from Hannes
    Frederic Sowa.

19) Fix early socket demux races that result in illegal dst reuse, from
    Eric Dumazet.

20) Validate socket address length in pptp code, from WANG Cong.

21) skb_reorder_vlan_header() uses incorrect offset and can corrupt
    packets, from Vlad Yasevich.

22) Fix memory leaks in nl80211 registry code, from Ola Olsson.

23) Timeout loop count handing fixes in mISDN, xgbe, qlge, sfc, and
    qlcnic.  From Dan Carpenter.

24) msg.msg_iocb needs to be cleared in recvfrom() otherwise, for
    example, AF_ALG will interpret it as an async call.  From Tadeusz
    Struk.

25) inetpeer_set_addr_v4 forgets to initialize the 'vif' field, from
    Eric Dumazet.

26) rhashtable enforces the minimum table size not early enough,
    breaking how we calculate the per-cpu lock allocations.  From
    Herbert Xu.

27) Fix FCC port lockup in 82xx driver, from Martin Roth.

28) FOU sockets need to be freed using RCU, from Hannes Frederic Sowa.

29) Fix out-of-bounds access in __skb_complete_tx_timestamp() and
    sock_setsockopt() wrt.  timestamp handling.  From WANG Cong.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (117 commits)
  net: check both type and procotol for tcp sockets
  drivers: net: xgene: fix Tx flow control
  tcp: restore fastopen with no data in SYN packet
  af_unix: Revert 'lock_interruptible' in stream receive code
  fou: clean up socket with kfree_rcu
  82xx: FCC: Fixing a bug causing to FCC port lock-up
  gianfar: Don't enable RX Filer if not supported
  net: fix warnings in 'make htmldocs' by moving macro definition out of field declaration
  rhashtable: Fix walker list corruption
  rhashtable: Enforce minimum size on initial hash table
  inet: tcp: fix inetpeer_set_addr_v4()
  ipv6: automatically enable stable privacy mode if stable_secret set
  net: fix uninitialized variable issue
  bluetooth: Validate socket address length in sco_sock_bind().
  net_sched: make qdisc_tree_decrease_qlen() work for non mq
  ser_gigaset: remove unnecessary kfree() calls from release method
  ser_gigaset: fix deallocation of platform device structure
  ser_gigaset: turn nonsense checks into WARN_ON
  ser_gigaset: fix up NULL checks
  qlcnic: fix a timeout loop
  ...

Dmitry reported the following out-of-bound access:

Call Trace:
 [<ffffffff816cec2e>] __asan_report_load4_noabort+0x3e/0x40
mm/kasan/report.c:294
 [<ffffffff84affb14>] sock_setsockopt+0x1284/0x13d0 net/core/sock.c:880
 [<     inline     >] SYSC_setsockopt net/socket.c:1746
 [<ffffffff84aed7ee>] SyS_setsockopt+0x1fe/0x240 net/socket.c:1729
 [<ffffffff85c18c76>] entry_SYSCALL_64_fastpath+0x16/0x7a
arch/x86/entry/entry_64.S:185

This is because we mistake a raw socket as a tcp socket.
We should check both sk->sk_type and sk->sk_protocol to ensure
it is a tcp socket.

Willem points out __skb_complete_tx_timestamp() needs to fix as well.
Reported-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Acked-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently the Tx flow control is based on reading the hardware state,
which is not accurate since it may not reflect the descriptors that
are not yet reached the memory.

To accurately control the Tx flow, changing it to be software based.
Signed-off-by: NIyappan Subramanian <isubramanian@apm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Yuchung tracked a regression caused by commit 57be5bda ("ip: convert
tcp_sendmsg() to iov_iter primitives") for TCP Fast Open.

Some Fast Open users do not actually add any data in the SYN packet.

Fixes: 57be5bda ("ip: convert tcp_sendmsg() to iov_iter primitives")
Reported-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: NYuchung Cheng <ycheng@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>