`ni6501_alloc_usb_buffers()` is called from `ni6501_auto_attach()` to
allocate RX and TX buffers for USB transfers.  It allocates
`devpriv->usb_rx_buf` followed by `devpriv->usb_tx_buf`.  If the
allocation of `devpriv->usb_tx_buf` fails, it frees
`devpriv->usb_rx_buf`, leaving the pointer set dangling, and returns an
error.  Later, `ni6501_detach()` will be called from the core comedi
module code to clean up.  `ni6501_detach()` also frees both
`devpriv->usb_rx_buf` and `devpriv->usb_tx_buf`, but
`devpriv->usb_rx_buf` may have already beed freed, leading to a
double-free error.  Fix it bu removing the call to
`kfree(devpriv->usb_rx_buf)` from `ni6501_alloc_usb_buffers()`, relying
on `ni6501_detach()` to free the memory.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

If `ni6501_auto_attach()` returns an error, the core comedi module code
will call `ni6501_detach()` to clean up.  If `ni6501_auto_attach()`
successfully allocated the comedi device private data, `ni6501_detach()`
assumes that a `struct mutex mut` contained in the private data has been
initialized and uses it.  Unfortunately, there are a couple of places
where `ni6501_auto_attach()` can return an error after allocating the
device private data but before initializing the mutex, so this
assumption is invalid.  Fix it by initializing the mutex just after
allocating the private data in `ni6501_auto_attach()` before any other
errors can be retturned.  Also move the call to `usb_set_intfdata()`
just to keep the code a bit neater (either position for the call is
fine).

I believe this was the cause of the following syzbot crash report
<https://syzkaller.appspot.com/bug?extid=cf4f2b6c24aff0a3edf6>:

usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
usb 1-1: string descriptor 0 read error: -71
comedi comedi0: Wrong number of endpoints
ni6501 1-1:0.233: driver 'ni6501' failed to auto-configure device.
INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 0 PID: 585 Comm: kworker/0:3 Not tainted 5.1.0-rc4-319354-g9a33b36 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xe8/0x16e lib/dump_stack.c:113
 assign_lock_key kernel/locking/lockdep.c:786 [inline]
 register_lock_class+0x11b8/0x1250 kernel/locking/lockdep.c:1095
 __lock_acquire+0xfb/0x37c0 kernel/locking/lockdep.c:3582
 lock_acquire+0x10d/0x2f0 kernel/locking/lockdep.c:4211
 __mutex_lock_common kernel/locking/mutex.c:925 [inline]
 __mutex_lock+0xfe/0x12b0 kernel/locking/mutex.c:1072
 ni6501_detach+0x5b/0x110 drivers/staging/comedi/drivers/ni_usb6501.c:567
 comedi_device_detach+0xed/0x800 drivers/staging/comedi/drivers.c:204
 comedi_device_cleanup.part.0+0x68/0x140 drivers/staging/comedi/comedi_fops.c:156
 comedi_device_cleanup drivers/staging/comedi/comedi_fops.c:187 [inline]
 comedi_free_board_dev.part.0+0x16/0x90 drivers/staging/comedi/comedi_fops.c:190
 comedi_free_board_dev drivers/staging/comedi/comedi_fops.c:189 [inline]
 comedi_release_hardware_device+0x111/0x140 drivers/staging/comedi/comedi_fops.c:2880
 comedi_auto_config.cold+0x124/0x1b0 drivers/staging/comedi/drivers.c:1068
 usb_probe_interface+0x31d/0x820 drivers/usb/core/driver.c:361
 really_probe+0x2da/0xb10 drivers/base/dd.c:509
 driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
 __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
 bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
 __device_attach+0x223/0x3a0 drivers/base/dd.c:844
 bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
 device_add+0xad2/0x16e0 drivers/base/core.c:2106
 usb_set_configuration+0xdf7/0x1740 drivers/usb/core/message.c:2021
 generic_probe+0xa2/0xda drivers/usb/core/generic.c:210
 usb_probe_device+0xc0/0x150 drivers/usb/core/driver.c:266
 really_probe+0x2da/0xb10 drivers/base/dd.c:509
 driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
 __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
 bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
 __device_attach+0x223/0x3a0 drivers/base/dd.c:844
 bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
 device_add+0xad2/0x16e0 drivers/base/core.c:2106
 usb_new_device.cold+0x537/0xccf drivers/usb/core/hub.c:2534
 hub_port_connect drivers/usb/core/hub.c:5089 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
 port_event drivers/usb/core/hub.c:5350 [inline]
 hub_event+0x138e/0x3b00 drivers/usb/core/hub.c:5432
 process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
 worker_thread+0x9b/0xe20 kernel/workqueue.c:2415
 kthread+0x313/0x420 kernel/kthread.c:253
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Reported-by: syzbot+cf4f2b6c24aff0a3edf6@syzkaller.appspotmail.com
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Unexpected out-of-bound data will be read in erofs_read_raw_page
after commit 07173c3e ("block: enable multipage bvecs") since
one iovec could have multiple pages.

Let's fix as what Ming's pointed out in the previous email [1].

[1] https://lore.kernel.org/lkml/20190411080953.GE421@ming.t460p/Suggested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Fixes: 07173c3e ("block: enable multipage bvecs")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

`vmk80xx_alloc_usb_buffers()` is called from `vmk80xx_auto_attach()` to
allocate RX and TX buffers for USB transfers.  It allocates
`devpriv->usb_rx_buf` followed by `devpriv->usb_tx_buf`.  If the
allocation of `devpriv->usb_tx_buf` fails, it frees
`devpriv->usb_rx_buf`,  leaving the pointer set dangling, and returns an
error.  Later, `vmk80xx_detach()` will be called from the core comedi
module code to clean up.  `vmk80xx_detach()` also frees both
`devpriv->usb_rx_buf` and `devpriv->usb_tx_buf`, but
`devpriv->usb_rx_buf` may have already been freed, leading to a
double-free error.  Fix it by removing the call to
`kfree(devpriv->usb_rx_buf)` from `vmk80xx_alloc_usb_buffers()`, relying
on `vmk80xx_detach()` to free the memory.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

If `vmk80xx_auto_attach()` returns an error, the core comedi module code
will call `vmk80xx_detach()` to clean up.  If `vmk80xx_auto_attach()`
successfully allocated the comedi device private data,
`vmk80xx_detach()` assumes that a `struct semaphore limit_sem` contained
in the private data has been initialized and uses it.  Unfortunately,
there are a couple of places where `vmk80xx_auto_attach()` can return an
error after allocating the device private data but before initializing
the semaphore, so this assumption is invalid.  Fix it by initializing
the semaphore just after allocating the private data in
`vmk80xx_auto_attach()` before any other errors can be returned.

I believe this was the cause of the following syzbot crash report
<https://syzkaller.appspot.com/bug?extid=54c2f58f15fe6876b6ad>:

usb 1-1: config 0 has no interface number 0
usb 1-1: New USB device found, idVendor=10cf, idProduct=8068, bcdDevice=e6.8d
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
vmk80xx 1-1:0.117: driver 'vmk80xx' failed to auto-configure device.
INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.1.0-rc4-319354-g9a33b36 #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xe8/0x16e lib/dump_stack.c:113
 assign_lock_key kernel/locking/lockdep.c:786 [inline]
 register_lock_class+0x11b8/0x1250 kernel/locking/lockdep.c:1095
 __lock_acquire+0xfb/0x37c0 kernel/locking/lockdep.c:3582
 lock_acquire+0x10d/0x2f0 kernel/locking/lockdep.c:4211
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x44/0x60 kernel/locking/spinlock.c:152
 down+0x12/0x80 kernel/locking/semaphore.c:58
 vmk80xx_detach+0x59/0x100 drivers/staging/comedi/drivers/vmk80xx.c:829
 comedi_device_detach+0xed/0x800 drivers/staging/comedi/drivers.c:204
 comedi_device_cleanup.part.0+0x68/0x140 drivers/staging/comedi/comedi_fops.c:156
 comedi_device_cleanup drivers/staging/comedi/comedi_fops.c:187 [inline]
 comedi_free_board_dev.part.0+0x16/0x90 drivers/staging/comedi/comedi_fops.c:190
 comedi_free_board_dev drivers/staging/comedi/comedi_fops.c:189 [inline]
 comedi_release_hardware_device+0x111/0x140 drivers/staging/comedi/comedi_fops.c:2880
 comedi_auto_config.cold+0x124/0x1b0 drivers/staging/comedi/drivers.c:1068
 usb_probe_interface+0x31d/0x820 drivers/usb/core/driver.c:361
 really_probe+0x2da/0xb10 drivers/base/dd.c:509
 driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
 __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
 bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
 __device_attach+0x223/0x3a0 drivers/base/dd.c:844
 bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
 device_add+0xad2/0x16e0 drivers/base/core.c:2106
 usb_set_configuration+0xdf7/0x1740 drivers/usb/core/message.c:2021
 generic_probe+0xa2/0xda drivers/usb/core/generic.c:210
 usb_probe_device+0xc0/0x150 drivers/usb/core/driver.c:266
 really_probe+0x2da/0xb10 drivers/base/dd.c:509
 driver_probe_device+0x21d/0x350 drivers/base/dd.c:671
 __device_attach_driver+0x1d8/0x290 drivers/base/dd.c:778
 bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:454
 __device_attach+0x223/0x3a0 drivers/base/dd.c:844
 bus_probe_device+0x1f1/0x2a0 drivers/base/bus.c:514
 device_add+0xad2/0x16e0 drivers/base/core.c:2106
 usb_new_device.cold+0x537/0xccf drivers/usb/core/hub.c:2534
 hub_port_connect drivers/usb/core/hub.c:5089 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5204 [inline]
 port_event drivers/usb/core/hub.c:5350 [inline]
 hub_event+0x138e/0x3b00 drivers/usb/core/hub.c:5432
 process_one_work+0x90f/0x1580 kernel/workqueue.c:2269
 worker_thread+0x9b/0xe20 kernel/workqueue.c:2415
 kthread+0x313/0x420 kernel/kthread.c:253
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352

Reported-by: syzbot+54c2f58f15fe6876b6ad@syzkaller.appspotmail.com
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch uses the device description to clearly identity a device
attached to the bus. It is needed as the currently useed mdevX
notation is not sufficiant in case more than one network
interface controller is being used at the same time.

Cc: stable@vger.kernel.org
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Merge tag 'iio-fixes-for-5.1a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-linus

Jonathan writes:

First set of IIO fixes for the 5.1 cycle.

Mostly the usual mix, but the bme680 SPI fix is much larger than
I would normally like.  It never worked, but conversely we have
code there that would make people expect it to do so.  Chances
of side effects are very low.

* core
  - Fix an uninitialised bitaks that could potentially result in random
    channels being enabled on startup.
* ad7192
  - Fix a wrong channel address for ad7193.
* ade7854
  - Fix a typo that results in returning peak voltage instead of peak current.
* at91
  - Fix a potential hang due to a race on interrupt setting.
* bmg160
  - Fix scale factor of temperature
* bme680
  - Fix scale factor of temperature
  - Fix SPI read interface.  This is a bit of a large patch as it seems
    that it never worked.  It's major for this driver but is unlikely to
    have any negative side effects.
* kxcjk1013
  - restore sensor range setting after resume.
* mcp4725
  - make sure to store powerdown bits when storing to the eeprom.
* mpu3050
  - Mask the chip ID correctly as we have chips that set the bother bits of
    this register.
* sgp30
  - Fix a missing Kconfig block that means the driver doesn't actually ever
    get built.

* tag 'iio-fixes-for-5.1a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio:
  iio: core: fix a possible circular locking dependency
  iio: ad_sigma_delta: select channel when reading register
  iio: pms7003: select IIO_TRIGGERED_BUFFER
  iio: cros_ec: Fix the maths for gyro scale calculation
  iio: adc: xilinx: prevent touching unclocked h/w on remove
  iio: adc: xilinx: fix potential use-after-free on probe
  iio: adc: xilinx: fix potential use-after-free on remove
  iio: dac: mcp4725: add missing powerdown bits in store eeprom
  io: accel: kxcjk1013: restore the range after resume.
  iio:chemical:bme680: Fix SPI read interface
  iio:chemical:bme680: Fix, report temperature in millidegrees
  iio: chemical: fix missing Kconfig block for sgp30
  iio: adc: at91: disable adc channel interrupt in timeout case
  iio: gyro: mpu3050: fix chip ID reading
  iio: Fix scan mask selection
  staging: iio: ad7192: Fix ad7193 channel address
  iio/gyro/bmg160: Use millidegrees for temperature scale
  Staging: iio: meter: fixed typo

Pull KVM fixes from Paolo Bonzini:
 "A collection of x86 and ARM bugfixes, and some improvements to
  documentation.

  On top of this, a cleanup of kvm_para.h headers, which were exported
  by some architectures even though they not support KVM at all. This is
  responsible for all the Kbuild changes in the diffstat"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (28 commits)
  Documentation: kvm: clarify KVM_SET_USER_MEMORY_REGION
  KVM: doc: Document the life cycle of a VM and its resources
  KVM: selftests: complete IO before migrating guest state
  KVM: selftests: disable stack protector for all KVM tests
  KVM: selftests: explicitly disable PIE for tests
  KVM: selftests: assert on exit reason in CR4/cpuid sync test
  KVM: x86: update %rip after emulating IO
  x86/kvm/hyper-v: avoid spurious pending stimer on vCPU init
  kvm/x86: Move MSR_IA32_ARCH_CAPABILITIES to array emulated_msrs
  KVM: x86: Emulate MSR_IA32_ARCH_CAPABILITIES on AMD hosts
  kvm: don't redefine flags as something else
  kvm: mmu: Used range based flushing in slot_handle_level_range
  KVM: export <linux/kvm_para.h> and <asm/kvm_para.h> iif KVM is supported
  KVM: x86: remove check on nr_mmu_pages in kvm_arch_commit_memory_region()
  kvm: nVMX: Add a vmentry check for HOST_SYSENTER_ESP and HOST_SYSENTER_EIP fields
  KVM: SVM: Workaround errata#1096 (insn_len maybe zero on SMAP violation)
  KVM: Reject device ioctls from processes other than the VM's creator
  KVM: doc: Fix incorrect word ordering regarding supported use of APIs
  KVM: x86: fix handling of role.cr4_pae and rename it to 'gpte_size'
  KVM: nVMX: Do not inherit quadrant and invalid for the root shadow EPT
  ...

Pull x86 fixes from Thomas Gleixner:
 "A pile of x86 updates:

   - Prevent exceeding he valid physical address space in the /dev/mem
     limit checks.

   - Move all header content inside the header guard to prevent compile
     failures.

   - Fix the bogus __percpu annotation in this_cpu_has() which makes
     sparse very noisy.

   - Disable switch jump tables completely when retpolines are enabled.

   - Prevent leaking the trampoline address"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/realmode: Make set_real_mode_mem() static inline
  x86/cpufeature: Fix __percpu annotation in this_cpu_has()
  x86/mm: Don't exceed the valid physical address space
  x86/retpolines: Disable switch jump tables when retpolines are enabled
  x86/realmode: Don't leak the trampoline kernel address
  x86/boot: Fix incorrect ifdeffery scope
  x86/resctrl: Remove unused variable

Pull perf tooling fixes from Thomas Gleixner:
 "Core libraries:
   - Fix max perf_event_attr.precise_ip detection.
   - Fix parser error for uncore event alias
   - Fixup ordering of kernel maps after obtaining the main kernel map
     address.

  Intel PT:
   - Fix TSC slip where A TSC packet can slip past MTC packets so that
     the timestamp appears to go backwards.
   - Fixes for exported-sql-viewer GUI conversion to python3.

  ARM coresight:
   - Fix the build by adding a missing case value for enumeration value
     introduced in newer library, that now is the required one.

  tool headers:
   - Syncronize kernel headers with the kernel, getting new io_uring and
     pidfd_send_signal syscalls so that 'perf trace' can handle them"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf pmu: Fix parser error for uncore event alias
  perf scripts python: exported-sql-viewer.py: Fix python3 support
  perf scripts python: exported-sql-viewer.py: Fix never-ending loop
  perf machine: Update kernel map address and re-order properly
  tools headers uapi: Sync powerpc's asm/kvm.h copy with the kernel sources
  tools headers: Update x86's syscall_64.tbl and uapi/asm-generic/unistd
  tools headers uapi: Update drm/i915_drm.h
  tools arch x86: Sync asm/cpufeatures.h with the kernel sources
  tools headers uapi: Sync linux/fcntl.h to get the F_SEAL_FUTURE_WRITE addition
  tools headers uapi: Sync asm-generic/mman-common.h and linux/mman.h
  perf evsel: Fix max perf_event_attr.precise_ip detection
  perf intel-pt: Fix TSC slip
  perf cs-etm: Add missing case value

Pull CPU hotplug fixes from Thomas Gleixner:
 "Two SMT/hotplug related fixes:

   - Prevent crash when HOTPLUG_CPU is disabled and the CPU bringup
     aborts. This is triggered with the 'nosmt' command line option, but
     can happen by any abort condition. As the real unplug code is not
     compiled in, prevent the fail by keeping the CPU in zombie state.

   - Enforce HOTPLUG_CPU for SMP on x86 to avoid the above situation
     completely. With 'nosmt' being a popular option it's required to
     unplug the half brought up sibling CPUs (due to the MCE wreckage)
     completely"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/smp: Enforce CONFIG_HOTPLUG_CPU when SMP=y
  cpu/hotplug: Prevent crash when CPU bringup fails on CONFIG_HOTPLUG_CPU=n

Pull locking fixlet from Thomas Gleixner:
 "Trivial update to the maintainers file"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  MAINTAINERS: Remove deleted file from futex file pattern

Pull core fixes from Thomas Gleixner:
 "A small set of core updates:

   - Make the watchdog respect the selected CPU mask again. That was
     broken by the rework of the watchdog thread management and caused
     inconsistent state and NMI watchdog being unstoppable.

   - Ensure that the objtool build can find the libelf location.

   - Remove dead kcore stub code"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  watchdog: Respect watchdog cpumask on CPU hotplug
  objtool: Query pkg-config for libelf location
  proc/kcore: Remove unused kclist_add_remap()

Pull powerpc fixes from Michael Ellerman:
 "Three non-regression fixes.

   - Our optimised memcmp could read past the end of one of the buffers
     and potentially trigger a page fault leading to an oops.

   - Some of our code to read energy management data on PowerVM had an
     endian bug leading to bogus results.

   - When reporting a machine check exception we incorrectly reported
     TLB multihits as D-Cache multhits due to a missing entry in the
     array of causes.

  Thanks to: Chandan Rajendra, Gautham R. Shenoy, Mahesh Salgaonkar,
  Segher Boessenkool, Vaidyanathan Srinivasan"

* tag 'powerpc-5.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/pseries/mce: Fix misleading print for TLB mutlihit
  powerpc/pseries/energy: Use OF accessor functions to read ibm,drc-indexes
  powerpc/64: Fix memcmp reading past the end of src/dest

Pull dmaengine fixes from Vinod Koul:

 - Revert "dmaengine: stm32-mdma: Add a check on read_u32_array" as that
   caused regression

 - Fix MAINTAINER file uniphier-mdmac.c file path

* tag 'dmaengine-fix-5.1-rc3' of git://git.infradead.org/users/vkoul/slave-dma:
  MAINTAINERS: Fix uniphier-mdmac.c file path
  dmaengine: stm32-mdma: Revert "dmaengine: stm32-mdma: Add a check on read_u32_array"

This fixes a possible circular locking dependency detected warning seen
with:
- CONFIG_PROVE_LOCKING=y
- consumer/provider IIO devices (ex: "voltage-divider" consumer of "adc")

When using the IIO consumer interface, e.g. iio_channel_get(), the consumer
device will likely call iio_read_channel_raw() or similar that rely on
'info_exist_lock' mutex.

typically:
...
	mutex_lock(&chan->indio_dev->info_exist_lock);
	if (chan->indio_dev->info == NULL) {
		ret = -ENODEV;
		goto err_unlock;
	}
	ret = do_some_ops()
err_unlock:
	mutex_unlock(&chan->indio_dev->info_exist_lock);
	return ret;
...

Same mutex is also hold in iio_device_unregister().

The following deadlock warning happens when:
- the consumer device has called an API like iio_read_channel_raw()
  at least once.
- the consumer driver is unregistered, removed (unbind from sysfs)

======================================================
WARNING: possible circular locking dependency detected
4.19.24 #577 Not tainted
------------------------------------------------------
sh/372 is trying to acquire lock:
(kn->count#30){++++}, at: kernfs_remove_by_name_ns+0x3c/0x84

but task is already holding lock:
(&dev->info_exist_lock){+.+.}, at: iio_device_unregister+0x18/0x60

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&dev->info_exist_lock){+.+.}:
       __mutex_lock+0x70/0xa3c
       mutex_lock_nested+0x1c/0x24
       iio_read_channel_raw+0x1c/0x60
       iio_read_channel_info+0xa8/0xb0
       dev_attr_show+0x1c/0x48
       sysfs_kf_seq_show+0x84/0xec
       seq_read+0x154/0x528
       __vfs_read+0x2c/0x15c
       vfs_read+0x8c/0x110
       ksys_read+0x4c/0xac
       ret_fast_syscall+0x0/0x28
       0xbedefb60

-> #0 (kn->count#30){++++}:
       lock_acquire+0xd8/0x268
       __kernfs_remove+0x288/0x374
       kernfs_remove_by_name_ns+0x3c/0x84
       remove_files+0x34/0x78
       sysfs_remove_group+0x40/0x9c
       sysfs_remove_groups+0x24/0x34
       device_remove_attrs+0x38/0x64
       device_del+0x11c/0x360
       cdev_device_del+0x14/0x2c
       iio_device_unregister+0x24/0x60
       release_nodes+0x1bc/0x200
       device_release_driver_internal+0x1a0/0x230
       unbind_store+0x80/0x130
       kernfs_fop_write+0x100/0x1e4
       __vfs_write+0x2c/0x160
       vfs_write+0xa4/0x17c
       ksys_write+0x4c/0xac
       ret_fast_syscall+0x0/0x28
       0xbe906840

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&dev->info_exist_lock);
                               lock(kn->count#30);
                               lock(&dev->info_exist_lock);
  lock(kn->count#30);

 *** DEADLOCK ***
...

cdev_device_del() can be called without holding the lock. It should be safe
as info_exist_lock prevents kernelspace consumers to use the exported
routines during/after provider removal. cdev_device_del() is for userspace.

Help to reproduce:
See example: Documentation/devicetree/bindings/iio/afe/voltage-divider.txt
sysv {
	compatible = "voltage-divider";
	io-channels = <&adc 0>;
	output-ohms = <22>;
	full-ohms = <222>;
};

First, go to iio:deviceX for the "voltage-divider", do one read:
$ cd /sys/bus/iio/devices/iio:deviceX
$ cat in_voltage0_raw

Then, unbind the consumer driver. It triggers above deadlock warning.
$ cd /sys/bus/platform/drivers/iio-rescale/
$ echo sysv > unbind

Note I don't actually expect stable will pick this up all the
way back into IIO being in staging, but if's probably valid that
far back.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Fixes: ac917a81 ("staging:iio:core set the iio_dev.info pointer to null on unregister")
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Merge tag 'led-fixes-for-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds

Pull LED fixes from Jacek Anaszewski:

 - fix refcnt leak on interface rename

 - use memcpy in device_name_store() to avoid including garbage from a
   previous, longer value in the device_name

 - fix a potential NULL pointer dereference in case of_match_device()
   cannot find a match

* tag 'led-fixes-for-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds:
  leds: trigger: netdev: use memcpy in device_name_store
  leds: pca9532: fix a potential NULL pointer dereference
  leds: trigger: netdev: fix refcnt leak on interface rename

Pull GPIO fixes from Linus Walleij:
 "As you can see [in the git history] I was away on leave and Bartosz
  kindly stepped in and collected a slew of fixes, I pulled them into my
  tree in two sets and merged some two more fixes (fixing my own caused
  bugs) on top.

  Summary:

   - Revert the extended use of gpio_set_config() and think about how we
     can do this properly.

   - Fix up the SPI CS GPIO handling so it now works properly on the SPI
     bus children, as intended.

   - Error paths and driver fixes"

* tag 'gpio-v5.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
  gpio: mockup: use simple_read_from_buffer() in debugfs read callback
  gpio: of: Fix of_gpiochip_add() error path
  gpio: of: Check for "spi-cs-high" in child instead of parent node
  gpio: of: Check propname before applying "cs-gpios" quirks
  gpio: mockup: fix debugfs read
  Revert "gpio: use new gpio_set_config() helper in more places"
  gpio: aspeed: fix a potential NULL pointer dereference
  gpio: amd-fch: Fix bogus SPDX identifier
  gpio: adnp: Fix testing wrong value in adnp_gpio_direction_input
  gpio: exar: add a check for the return value of ida_simple_get fails

If userspace doesn't end the input with a newline (which can easily
happen if the write happens from a C program that does write(fd,
iface, strlen(iface))), we may end up including garbage from a
previous, longer value in the device_name. For example

# cat device_name

# printf 'eth12' > device_name
# cat device_name
eth12
# printf 'eth3' > device_name
# cat device_name
eth32

I highly doubt anybody is relying on this behaviour, so switch to
simply copying the bytes (we've already checked that size is <
IFNAMSIZ) and unconditionally zero-terminate it; of course, we also
still have to strip a trailing newline.

This is also preparation for future patches.

Fixes: 06f502f5 ("leds: trigger: Introduce a NETDEV trigger")
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

In case of_match_device cannot find a match, return -EINVAL to avoid
NULL pointer dereference.

Fixes: fa4191a6 ("leds: pca9532: Add device tree support")
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>

Pull staging driver fixes from Greg KH:
 "Here are some small staging driver fixes for 5.1-rc3, and one driver
  removal.

  The biggest thing here is the removal of the mt7621-eth driver as a
  "real" network driver was merged in 5.1-rc1 for this hardware, so this
  old driver can now be removed.

  Other than that, there are just a number of small fixes, all resolving
  reported issues and some potential corner cases for error handling
  paths.

  All of these have been in linux-next with no reported issues"

* tag 'staging-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: vt6655: Remove vif check from vnt_interrupt
  staging: erofs: keep corrupted fs from crashing kernel in erofs_readdir()
  staging: octeon-ethernet: fix incorrect PHY mode
  staging: vc04_services: Fix an error code in vchiq_probe()
  staging: erofs: fix error handling when failed to read compresssed data
  staging: vt6655: Fix interrupt race condition on device start up.
  staging: rtlwifi: Fix potential NULL pointer dereference of kzalloc
  staging: rtl8712: uninitialized memory in read_bbreg_hdl()
  staging: rtlwifi: rtl8822b: fix to avoid potential NULL pointer dereference
  staging: rtl8188eu: Fix potential NULL pointer dereference of kcalloc
  staging, mt7621-pci: fix build without pci support
  staging: speakup_soft: Fix alternate speech with other synths
  staging: axis-fifo: add CONFIG_OF dependency
  staging: olpc_dcon_xo_1: add missing 'const' qualifier
  staging: comedi: ni_mio_common: Fix divide-by-zero for DIO cmdtest
  staging: erofs: fix to handle error path of erofs_vmap()
  staging: mt7621-dts: update ethernet settings.
  staging: remove mt7621-eth

Pull tty/serial fixes from Greg KH:
 "Here are some small tty and serial driver fixes for 5.1-rc3.

  Nothing major here, just a number of potential problems fixes for
  error handling paths, as well as some other minor bugfixes for
  reported issues with 5.1-rc1.

  All of these have been in linux-next with no reported issues"

* tag 'tty-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: fix NULL pointer issue when tty_port ops is not set
  Disable kgdboc failed by echo space to /sys/module/kgdboc/parameters/kgdboc
  dt-bindings: serial: Add compatible for Mediatek MT8183
  tty/serial: atmel: RS485 HD w/DMA: enable RX after TX is stopped
  tty/serial: atmel: Add is_half_duplex helper
  serial: sh-sci: Fix setting SCSCR_TIE while transferring data
  serial: ar933x_uart: Fix build failure with disabled console
  tty: serial: qcom_geni_serial: Initialize baud in qcom_geni_console_setup
  sc16is7xx: missing unregister/delete driver on error in sc16is7xx_init()
  tty: mxs-auart: fix a potential NULL pointer dereference
  tty: atmel_serial: fix a potential NULL pointer dereference
  serial: max310x: Fix to avoid potential NULL pointer dereference
  serial: mvebu-uart: Fix to avoid a potential NULL pointer dereference

Pull USB fixes from Greg KH:
 "Here are some small USB fixes for 5.1-rc3.

  Nothing major at all here, just a small collection of fixes for
  reported issues, and potential problems with error handling paths.
  Also a few new device ids, as normal.

  All of these have been in linux-next with no reported issues"

* tag 'usb-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (25 commits)
  USB: serial: option: add Olicard 600
  USB: serial: cp210x: add new device id
  usb: u132-hcd: fix resource leak
  usb: cdc-acm: fix race during wakeup blocking TX traffic
  usb: mtu3: fix EXTCON dependency
  usb: usb251xb: fix to avoid potential NULL pointer dereference
  usb: core: Try generic PHY_MODE_USB_HOST if usb_phy_roothub_set_mode fails
  phy: sun4i-usb: Support set_mode to USB_HOST for non-OTG PHYs
  xhci: Don't let USB3 ports stuck in polling state prevent suspend
  usb: xhci: dbc: Don't free all memory with spinlock held
  xhci: Fix port resume done detection for SS ports with LPM enabled
  USB: serial: mos7720: fix mos_parport refcount imbalance on error path
  USB: gadget: f_hid: fix deadlock in f_hidg_write()
  usb: gadget: net2272: Fix net2272_dequeue()
  usb: gadget: net2280: Fix net2280_dequeue()
  usb: gadget: net2280: Fix overrun of OUT messages
  usb: dwc3: pci: add support for Comet Lake PCH ID
  usb: usb251xb: Remove unnecessary comparison of unsigned integer with >= 0
  usb: common: Consider only available nodes for dr_mode
  usb: typec: tcpm: Try PD-2.0 if sink does not respond to 3.0 source-caps
  ...

Pull ACPI fix from Rafael Wysocki:
 "This corrects a previous attempt to make Linux use its own set of ACPI
  debug flags different from the upstream ACPICA's default (Erik
  Schmauss)"

* tag 'acpi-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: use different default debug value than ACPICA

Pull power management fixes from Rafael Wysocki:
 "These fix CPU base frequency reporting in the intel_pstate driver and
  a use-after-free in the scpi-cpufreq driver.

  Specifics:

   - Fix the ACPI CPPC library to actually follow the specification when
     decoding the guaranteed performance register information and make
     the intel_pstate driver to fall back to the nominal frequency when
     reporting the base frequency if the guaranteed performance register
     information is not there (Srinivas Pandruvada).

   - Fix use-after-free in the exit callback of the scpi-cpufreq left
     after an update during the 5.0 development cycle (Vincent Stehlé)"

* tag 'pm-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpufreq: scpi: Fix use after free
  cpufreq: intel_pstate: Also use CPPC nominal_perf for base_frequency
  ACPI / CPPC: Fix guaranteed performance handling

Pull security layer fixes from James Morris:
 "Yama and LSM config fixes"

* 'fixes-v5.1-a' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  LSM: Revive CONFIG_DEFAULT_SECURITY_* for "make oldconfig"
  Yama: mark local symbols as static

Merge misc fixes from Andrew Morton:
 "22 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (22 commits)
  fs/proc/proc_sysctl.c: fix NULL pointer dereference in put_links
  fs: fs_parser: fix printk format warning
  checkpatch: add %pt as a valid vsprintf extension
  mm/migrate.c: add missing flush_dcache_page for non-mapped page migrate
  drivers/block/zram/zram_drv.c: fix idle/writeback string compare
  mm/page_isolation.c: fix a wrong flag in set_migratetype_isolate()
  mm/memory_hotplug.c: fix notification in offline error path
  ptrace: take into account saved_sigmask in PTRACE{GET,SET}SIGMASK
  fs/proc/kcore.c: make kcore_modules static
  include/linux/list.h: fix list_is_first() kernel-doc
  mm/debug.c: fix __dump_page when mapping->host is not set
  mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified
  include/linux/hugetlb.h: convert to use vm_fault_t
  iommu/io-pgtable-arm-v7s: request DMA32 memory, and improve debugging
  mm: add support for kmem caches in DMA32 zone
  ocfs2: fix inode bh swapping mixup in ocfs2_reflink_inodes_lock
  mm/hotplug: fix offline undo_isolate_page_range()
  fs/open.c: allow opening only regular files during execve()
  mailmap: add Changbin Du
  mm/debug.c: add a cast to u64 for atomic64_read()
  ...

Pull arm64 fix from Catalin Marinas:
 "Use memblock_alloc() instead of memblock_alloc_low() in
  request_standard_resources(), the latter being limited to the low 4G
  memory range on arm64"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: replace memblock_alloc_low with memblock_alloc

Pull IOMMU fixes from Joerg Roedel:

 - Fix a bug in the AMD IOMMU driver not handling exclusion ranges
   correctly. In fact the driver did not reserve these ranges for IOVA
   allocations, so that dma-handles could be allocated in an exclusion
   range, leading to data corruption. Exclusion ranges have not been
   used by any firmware up to now, so this issue remained undiscovered
   for quite some time.

 - Fix wrong warning messages that the IOMMU core code prints when it
   tries to allocate the default domain for an iommu group and the
   driver does not support any of the default domain types (like Intel
   VT-d).

* tag 'iommu-fixes-v5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu:
  iommu/amd: Reserve exclusion range in iova-domain
  iommu: Don't print warning when IOMMU driver only supports unmanaged domains

Pull driver core fix from Greg KH:
 "Here is a single driver core patch for 5.1-rc3.

  After 5.1-rc1, all of the users of BUS_ATTR() are finally removed, so
  we can now drop this macro from include/linux/device.h so that no more
  new users will be created.

  This patch has been in linux-next for a while, with no reported
  issues"

* tag 'driver-core-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  driver core: remove BUS_ATTR()

Pull char/misc driver fixes from Greg KH:
 "Here are some binder, habanalabs, and vboxguest driver fixes for
  5.1-rc3.

  The Binder fixes resolve some reported issues found by testing, first
  by the selinux developers, and then earlier today by syzbot.

  The habanalabs fixes are all minor, resolving a number of tiny things.

  The vboxguest patches are a bit larger. They resolve the fact that
  virtual box decided to change their api in their latest release in a
  way that broke the existing kernel code, despite saying that they were
  never going to do that. So this is a bit of a "new feature", but is
  good to get merged so that 5.1 will work with the latest release. The
  changes are not large and of course virtual box "swears" they will not
  break this again, but no one is holding their breath here.

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

* tag 'char-misc-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  virt: vbox: Implement passing requestor info to the host for VirtualBox 6.0.x
  binder: fix race between munmap() and direct reclaim
  binder: fix BUG_ON found by selinux-testsuite
  habanalabs: cast to expected type
  habanalabs: prevent host crash during suspend/resume
  habanalabs: perform accounting for active CS
  habanalabs: fix mapping with page size bigger than 4KB
  habanalabs: complete user context cleanup before hard reset
  habanalabs: fix bug when mapping very large memory area
  habanalabs: fix MMU number of pages calculation

Pull SCSI fixes from James Bottomley:
 "Thirteen fixes, seven of which are for IBM fibre channel and three
  additional for fairly serious bugs in drivers (qla2xxx, mpt3sas,
  aacraid).

  Of the three core fixes, the most significant is probably the missed
  run queue causing an indefinite hang. The others are fixing a
  potential use after free on device close and silencing an incorrect
  warning"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: ibmvfc: Clean up transport events
  scsi: ibmvfc: Byte swap status and error codes when logging
  scsi: ibmvfc: Add failed PRLI to cmd_status lookup array
  scsi: ibmvfc: Remove "failed" from logged errors
  scsi: zfcp: reduce flood of fcrscn1 trace records on multi-element RSCN
  scsi: zfcp: fix scsi_eh host reset with port_forced ERP for non-NPIV FCP devices
  scsi: zfcp: fix rport unblock if deleted SCSI devices on Scsi_Host
  scsi: sd: Quiesce warning if device does not report optimal I/O size
  scsi: sd: Fix a race between closing an sd device and sd I/O
  scsi: core: Run queue when state is set to running after being blocked
  scsi: qla4xxx: fix a potential NULL pointer dereference
  scsi: aacraid: Insure we don't access PCIe space during AER/EEH
  scsi: mpt3sas: Fix kernel panic during expander reset

Pull i2c fixes from Wolfram Sang:
 "A new ID for the i801 driver and some Documentation fixes to make it
  easier for people to find the bindings (which is also a basis for
  further improvements in that area)"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: wmt: make bindings file name match the driver
  i2c: sun6i-p2wi: make bindings file name match the driver
  i2c: stu300: make bindings file name match the driver
  i2c: mt65xx: make bindings file name match the driver
  i2c: iop3xx: make bindings file name match the driver
  i2c: i801: Add support for Intel Comet Lake

Pull sound fixes from Takashi Iwai:
 "The important fixes at this time are a couple fixes in ALSA core: a
  fix for PCM is about the OOB access in PCM OSS plugins that has been
  for long time, but hasn't hit so often until now just because we
  allocated a large buffer via vmalloc(), and surfaced more often after
  switching to kvmalloc(). Another fix is for a long-standing PCM
  problem wrt racy PM resume.

  Others are trivial nospec coverage and usual HD-audio quirks"

* tag 'sound-5.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda/realtek - Fix speakers on Acer Predator Helios 500 Ryzen laptops
  ALSA: pcm: Don't suspend stream in unrecoverable PCM state
  ALSA: hda/ca0132 - Simplify alt firmware loading code
  ALSA: pcm: Fix possible OOB access in PCM oss plugins
  ALSA: hda/realtek: Enable headset MIC of ASUS X430UN and X512DK with ALC256
  ALSA: hda/realtek: Enable headset mic of ASUS P5440FF with ALC256
  ALSA: hda/realtek: Enable ASUS X441MB and X705FD headset MIC with ALC256
  ALSA: hda/realtek - Add support for Acer Aspire E5-523G/ES1-432 headset mic
  ALSA: hda/realtek: Enable headset MIC of Acer Aspire Z24-890 with ALC286
  ALSA: seq: oss: Fix Spectre v1 vulnerability
  ALSA: rawmidi: Fix potential Spectre v1 vulnerability

Merge tag 'kbuild-fixes-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Remove harmful -Oz option of Clang

 - Get back the original behavior (no recursion for in-tree build) for
   GNU Make 4.x

 - Some minor fixes for coccinelle patches

 - Do not overwrite .gitignore in the output directory in case it is
   version-controlled

 - Fix missed record-mcount bug for dynamic ftrace

 - Fix endianness bug in modversions for relative CRC

 - Cater to '^H' key code in Kconfig ncurses programs

* tag 'kbuild-fixes-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kconfig/[mn]conf: handle backspace (^H) key
  kbuild: modversions: Fix relative CRC byte order interpretation
  scripts: coccinelle: Fix description of badty.cocci
  kbuild: strip whitespace in cmd_record_mcount findstring
  kbuild: do not overwrite .gitignore in output directory
  kbuild: skip parsing pre sub-make code for recursion
  coccinelle: put_device: reduce false positives
  kbuild: skip sub-make for in-tree build with GNU Make 4.x
  Revert "kbuild: use -Oz instead of -Os when using clang"

Pull block fixes from Jens Axboe:
 "Small set of fixes that should go into this series. This contains:

   - compat signal mask fix for io_uring (Arnd)

   - EAGAIN corner case for direct vs buffered writes for io_uring
     (Roman)

   - NVMe pull request from Christoph with various little fixes

   - sbitmap ws_active fix, which caused a perf regression for shared
     tags (me)

   - sbitmap bit ordering fix (Ming)

   - libata on-stack DMA fix (Raymond)"

* tag 'for-linus-20190329' of git://git.kernel.dk/linux-block:
  nvmet: fix error flow during ns enable
  nvmet: fix building bvec from sg list
  nvme-multipath: relax ANA state check
  nvme-tcp: fix an endianess miss-annotation
  libata: fix using DMA buffers on stack
  io_uring: offload write to async worker in case of -EAGAIN
  sbitmap: order READ/WRITE freed instance and setting clear bit
  blk-mq: fix sbitmap ws_active for shared tags
  io_uring: fix big-endian compat signal mask handling
  blk-mq: update comment for blk_mq_hctx_has_pending()
  blk-mq: use blk_mq_put_driver_tag() to put tag

Pull ceph fixes from Ilya Dryomov:
 "A patch to avoid choking on multipage bvecs in the messenger and a
  small use-after-free fix"

* tag 'ceph-for-5.1-rc3' of git://github.com/ceph/ceph-client:
  ceph: fix use-after-free on symlink traversal
  libceph: fix breakage caused by multipage bvecs

Pull xfs fixes from Darrick Wong:
 "Here are a few fixes for some corruption bugs and uninitialized
  variable problems. The few patches here have gone through a few days
  worth of fstest runs with no new problems observed.

  Changes since last update:

   - Fix a bunch of static checker complaints about uninitialized
     variables and insufficient range checks.

   - Avoid a crash when incore extent map data are corrupt.

   - Disallow FITRIM when we haven't recovered the log and know the
     metadata are stale.

   - Fix a data corruption when doing unaligned overlapping dio writes"

* tag 'xfs-5.1-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: serialize unaligned dio writes against all other dio writes
  xfs: prohibit fstrim in norecovery mode
  xfs: always init bma in xfs_bmapi_write
  xfs: fix btree scrub checking with regards to root-in-inode
  xfs: dabtree scrub needs to range-check level
  xfs: don't trip over uninitialized buffer on extent read of corrupted inode

Commit 70b62c25 ("LoadPin: Initialize as ordered LSM") removed
CONFIG_DEFAULT_SECURITY_{SELINUX,SMACK,TOMOYO,APPARMOR,DAC} from
security/Kconfig and changed CONFIG_LSM to provide a fixed ordering as a
default value. That commit expected that existing users (upgrading from
Linux 5.0 and earlier) will edit CONFIG_LSM value in accordance with
their CONFIG_DEFAULT_SECURITY_* choice in their old kernel configs. But
since users might forget to edit CONFIG_LSM value, this patch revives
the choice (only for providing the default value for CONFIG_LSM) in order
to make sure that CONFIG_LSM reflects CONFIG_DEFAULT_SECURITY_* from their
old kernel configs.

Note that since TOMOYO can be fully stacked against the other legacy
major LSMs, when it is selected, it explicitly disables the other LSMs
to avoid them also initializing since TOMOYO does not expect this
currently.
Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Fixes: 70b62c25 ("LoadPin: Initialize as ordered LSM")
Co-developed-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <james.morris@microsoft.com>