When we enable pointer authentication in the kernel, LR values saved to
the stack will have a PAC which we must strip in order to retrieve the
real return address.

Strip PACs when unwinding the stack in order to account for this.

When function graph tracer is used with patchable-function-entry then
return_to_handler will also have pac bits so strip it too.
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Re-position ptrauth_strip_insn_pac, comment]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Functions like vmap() record how much memory has been allocated by their
callers, and callers are identified using __builtin_return_address(). Once
the kernel is using pointer-auth the return address will be signed. This
means it will not match any kernel symbol, and will vary between threads
even for the same caller.

The output of /proc/vmallocinfo in this case may look like,
0x(____ptrval____)-0x(____ptrval____)   20480 0x86e28000100e7c60 pages=4 vmalloc N0=4
0x(____ptrval____)-0x(____ptrval____)   20480 0x86e28000100e7c60 pages=4 vmalloc N0=4
0x(____ptrval____)-0x(____ptrval____)   20480 0xc5c78000100e7c60 pages=4 vmalloc N0=4

The above three 64bit values should be the same symbol name and not
different LR values.

Use the pre-processor to add logic to clear the PAC to
__builtin_return_address() callers. This patch adds a new file
asm/compiler.h and is transitively included via include/compiler_types.h on
the compiler command line so it is guaranteed to be loaded and the users of
this macro will not find a wrong version.

Helper macros ptrauth_kernel_pac_mask/ptrauth_clear_pac are created for
this purpose and added in this file. Existing macro ptrauth_user_pac_mask
moved from asm/pointer_auth.h.
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

This patch uses the existing boot_init_stack_canary arch function
to initialize the ptrauth keys for the booting task in the primary
core. The requirement here is that it should be always inline and
the caller must never return.

As pointer authentication too detects a subset of stack corruption
so it makes sense to place this code here.

Both pointer authentication and stack canary codes are protected
by their respective config option.
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Set up keys to use pointer authentication within the kernel. The kernel
will be compiled with APIAKey instructions, the other keys are currently
unused. Each task is given its own APIAKey, which is initialized during
fork. The key is changed during context switch and on kernel entry from
EL0.

The keys for idle threads need to be set before calling any C functions,
because it is not possible to enter and exit a function with different
keys.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Modified secondary cores key structure, comments]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

When the kernel is compiled with pointer auth instructions, the boot CPU
needs to start using address auth very early, so change the cpucap to
account for this.

Pointer auth must be enabled before we call C functions, because it is
not possible to enter a function with pointer auth disabled and exit it
with pointer auth enabled. Note, mismatches between architected and
IMPDEF algorithms will still be caught by the cpufeature framework (the
separate *_ARCH and *_IMP_DEF cpucaps).

Note the change in behavior: if the boot CPU has address auth and a
late CPU does not, then the late CPU is parked by the cpufeature
framework. This is possible as kernel will only have NOP space intructions
for PAC so such mismatched late cpu will silently ignore those
instructions in C functions. Also, if the boot CPU does not have address
auth and the late CPU has then the late cpu will still boot but with
ptrauth feature disabled.

Leave generic authentication as a "system scope" cpucap for now, since
initially the kernel will only use address authentication.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Re-worked ptrauth setup logic, comments]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Each system capability can be of either boot, local, or system scope,
depending on when the state of the capability is finalized. When we
detect a conflict on a late CPU, we either offline the CPU or panic the
system. We currently always panic if the conflict is caused by a boot
scope capability, and offline the CPU if the conflict is caused by a
local or system scope capability.

We're going to want to add a new capability (for pointer authentication)
which needs to be boot scope but doesn't need to panic the system when a
conflict is detected. So add a new flag to specify whether the
capability requires the system to panic or not. Current boot scope
capabilities are updated to set the flag, so there should be no
functional change as a result of this patch.
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

These helpers are used only by functions inside cpufeature.c and
hence makes sense to be moved from cpufeature.h to cpufeature.c as
they are not expected to be used globally.

This change helps in reducing the header file size as well as to add
future cpu capability types without confusion. Only a cpu capability
type macro is sufficient to expose those capabilities globally.
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

This patch allows __cpu_setup to be invoked with one of these flags,
ARM64_CPU_BOOT_PRIMARY, ARM64_CPU_BOOT_SECONDARY or ARM64_CPU_RUNTIME.
This is required as some cpufeatures need different handling during
different scenarios.

The input parameter in x0 is preserved till the end to be used inside
this function.

There should be no functional change with this patch and is useful
for the subsequent ptrauth patch which utilizes it. Some upcoming
arm cpufeatures can also utilize these flags.
Suggested-by: James Morse <james.morse@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

As we're going to enable pointer auth within the kernel and use a
different APIAKey for the kernel itself, so move the user APIAKey
switch to EL0 exception return.

The other 4 keys could remain switched during task switch, but are also
moved to keep things consistent.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: commit msg, re-positioned the patch, comments]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

We currently enable ptrauth for userspace, but do not use it within the
kernel. We're going to enable it for the kernel, and will need to manage
a separate set of ptrauth keys for the kernel.

We currently keep all 5 keys in struct ptrauth_keys. However, as the
kernel will only need to use 1 key, it is a bit wasteful to allocate a
whole ptrauth_keys struct for every thread.

Therefore, a subsequent patch will define a separate struct, with only 1
key, for the kernel. In preparation for that, rename the existing struct
(and associated macros and functions) to reflect that they are specific
to userspace.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Re-positioned the patch to reduce the diff]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

To enable pointer auth for the kernel, we're going to need to check for
the presence of address auth and generic auth using alternative_if. We
currently have two cpucaps for each, but alternative_if needs to check a
single cpucap. So define meta-capabilities that are present when either
of the current two capabilities is present.

Leave the existing four cpucaps in place, as they are still needed to
check for mismatched systems where one CPU has the architected algorithm
but another has the IMP DEF algorithm.

Note, the meta-capabilities were present before but were removed in
commit a56005d3 ("arm64: cpufeature: Reduce number of pointer auth
CPU caps from 6 to 4") and commit 1e013d06 ("arm64: cpufeature: Rework
ptr auth hwcaps using multi_entry_cap_matches"), as they were not needed
then. Note, unlike before, the current patch checks the cpucap values
directly, instead of reading the CPU ID register value.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: commit message and macro rebase, use __system_matches_cap]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Some existing/future meta cpucaps match need the presence of individual
cpucaps. Currently the individual cpucaps checks it via an array based
flag and this introduces dependency on the array entry order.
This limitation exists only for system scope cpufeature.

This patch introduces an internal helper function (__system_matches_cap)
to invoke the matching handler for system scope. This helper has to be
used during a narrow window when,
- The system wide safe registers are set with all the SMP CPUs and,
- The SYSTEM_FEATURE cpu_hwcaps may not have been set.

Normal users should use the existing cpus_have_{const_}cap() global
function.
Suggested-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Pull btrfs fixes from David Sterba:
 "These are fixes that were found during testing with help of error
  injection, plus some other stable material.

  There's a fixup to patch added to rc1 causing locking in wrong context
  warnings, tests found one more deadlock scenario. The patches are
  tagged for stable, two of them now in the queue but we'd like all
  three released at the same time.

  I'm not happy about fixes to fixes in such a fast succession during
  rcs, but I hope we found all the fallouts of commit 28553fa9
  ('Btrfs: fix race between shrinking truncate and fiemap')"

* tag 'for-5.6-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix deadlock during fast fsync when logging prealloc extents beyond eof
  Btrfs: fix btrfs_wait_ordered_range() so that it waits for all ordered extents
  btrfs: fix bytes_may_use underflow in prealloc error condtition
  btrfs: handle logged extent failure properly
  btrfs: do not check delayed items are empty for single transaction cleanup
  btrfs: reset fs_root to NULL on error in open_ctree
  btrfs: destroy qgroup extent records on transaction abort

Pull ext4 fixes from Ted Ts'o:
 "More miscellaneous ext4 bug fixes (all stable fodder)"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix mount failure with quota configured as module
  jbd2: fix ocfs2 corrupt when clearing block group bits
  ext4: fix race between writepages and enabling EXT4_EXTENTS_FL
  ext4: rename s_journal_flag_rwsem to s_writepages_rwsem
  ext4: fix potential race between s_flex_groups online resizing and access
  ext4: fix potential race between s_group_info online resizing and access
  ext4: fix potential race between online resizing and write operations
  ext4: add cond_resched() to __ext4_find_entry()
  ext4: fix a data race in EXT4_I(inode)->i_disksize

Pull csky updates from Guo Ren:
 "Sorry, I missed 5.6-rc1 merge window, but in this pull request the
  most are the fixes and the rests are between fixes and features. The
  only outside modification is the MAINTAINERS file update with our
  mailing list.

   - cache flush implementation fixes

   - ftrace modify panic fix

   - CONFIG_SMP boot problem fix

   - fix pt_regs saving for atomic.S

   - fix fixaddr_init without highmem.

   - fix stack protector support

   - fix fake Tightly-Coupled Memory code compile and use

   - fix some typos and coding convention"

* tag 'csky-for-linus-5.6-rc3' of git://github.com/c-sky/csky-linux: (23 commits)
  csky: Replace <linux/clk-provider.h> by <linux/of_clk.h>
  csky: Implement copy_thread_tls
  csky: Add PCI support
  csky: Minimize defconfig to support buildroot config.fragment
  csky: Add setup_initrd check code
  csky: Cleanup old Kconfig options
  arch/csky: fix some Kconfig typos
  csky: Fixup compile warning for three unimplemented syscalls
  csky: Remove unused cache implementation
  csky: Fixup ftrace modify panic
  csky: Add flush_icache_mm to defer flush icache all
  csky: Optimize abiv2 copy_to_user_page with VM_EXEC
  csky: Enable defer flush_dcache_page for abiv2 cpus (807/810/860)
  csky: Remove unnecessary flush_icache_* implementation
  csky: Support icache flush without specific instructions
  csky/Kconfig: Add Kconfig.platforms to support some drivers
  csky/smp: Fixup boot failed when CONFIG_SMP
  csky: Set regs->usp to kernel sp, when the exception is from kernel
  csky/mm: Fixup export invalid_pte_table symbol
  csky: Separate fixaddr_init from highmem
  ...

The C-Sky platform code is not a clock provider, and just needs to call
of_clk_init().

Hence it can include <linux/of_clk.h> instead of <linux/clk-provider.h>.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

Pull RAS fixes from Thomas Gleixner:
 "Two fixes for the AMD MCE driver:

   - Populate the per CPU MCA bank descriptor pointer only after it has
     been completely set up to prevent a use-after-free in case that one
     of the subsequent initialization step fails

   - Implement a proper release function for the sysfs entries of MCA
     threshold controls instead of freeing the memory right in the CPU
     teardown code, which leads to another use-after-free when the
     associated sysfs file is opened and accessed"

* tag 'ras-urgent-2020-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mce/amd: Fix kobject lifetime
  x86/mce/amd: Publish the bank pointer only after setup has succeeded

Pull irq fixes from Thomas Gleixner:
 "Two fixes for the irq core code which are follow ups to the recent MSI
  fixes:

   - The WARN_ON which was put into the MSI setaffinity callback for
     paranoia reasons actually triggered via a callchain which escaped
     when all the possible ways to reach that code were analyzed.

     The proc/irq/$N/*affinity interfaces have a quirk which came in
     when ALPHA moved to the generic interface: In case that the written
     affinity mask does not contain any online CPU it calls into ALPHAs
     magic auto affinity setting code.

     A few years later this mechanism was also made available to x86 for
     no good reasons and in a way which circumvents all sanity checks
     for interrupts which cannot have their affinity set from process
     context on X86 due to the way the X86 interrupt delivery works.

     It would be possible to make this work properly, but there is no
     point in doing so. If the interrupt is not yet started then the
     affinity setting has no effect and if it is started already then it
     is already assigned to an online CPU so there is no point to
     randomly move it to some other CPU. Just return EINVAL as the code
     has done before that change forever.

   - The new MSI quirk bit in the irq domain flags turned out to be
     already occupied, which escaped the author and the reviewers
     because the already in use bits were 0,6,2,3,4,5 listed in that
     order.

     That bit 6 was simply overlooked because the ordering was straight
     forward linear otherwise. So the new bit ended up being a
     duplicate.

     Fix it up by switching the oddball 6 to the obvious 1"

* tag 'irq-urgent-2020-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq/irqdomain: Make sure all irq domain flags are distinct
  genirq/proc: Reject invalid affinity masks (again)

Pull x86 fixes from Thomas Gleixner:
 "Two fixes for x86:

   - Remove the __force_oder definiton from the kaslr boot code as it is
     already defined in the page table code which makes GCC 10 builds
     fail because it changed the default to -fno-common.

   - Address the AMD erratum 1054 concerning the IRPERF capability and
     enable the Instructions Retired fixed counter on machines which are
     not affected by the erratum"

* tag 'x86-urgent-2020-02-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu/amd: Enable the fixed Instructions Retired counter IRPERF
  x86/boot/compressed: Don't declare __force_order in kaslr_64.c

Pull zonefs fix from Damien Le Moal:
 "A single patch fixing typos in the documentation file"

* tag 'zonefs-5.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/zonefs:
  zonefs: fix documentation typos etc.

Pull io_uring fixes from Jens Axboe:
 "Here's a small collection of fixes that were queued up:

   - Remove unnecessary NULL check (Dan)

   - Missing io_req_cancelled() call in fallocate (Pavel)

   - Put the cleanup check for aux data in the right spot (Pavel)

   - Two fixes for SQPOLL (Stefano, Xiaoguang)"

* tag 'io_uring-5.6-2020-02-22' of git://git.kernel.dk/linux-block:
  io_uring: fix __io_iopoll_check deadlock in io_sq_thread
  io_uring: prevent sq_thread from spinning when it should stop
  io_uring: fix use-after-free by io_cleanup_req()
  io_uring: remove unnecessary NULL checks
  io_uring: add missing io_req_cancelled()

Pull block fixes from Jens Axboe:
 "Just a set of NVMe fixes via Keith"

* tag 'block-5.6-2020-02-22' of git://git.kernel.dk/linux-block:
  nvme-multipath: Fix memory leak with ana_log_buf
  nvme: Fix uninitialized-variable warning
  nvme-pci: Use single IRQ vector for old Apple models
  nvme/pci: Add sleep quirk for Samsung and Toshiba drives

Pull SCSI fixes from James Bottomley:
 "Four non-core fixes.

  Two are reverts of target fixes which turned out to have unwanted side
  effects, one is a revert of an RDMA fix with the same problem and the
  final one fixes an incorrect warning about memory allocation failures
  in megaraid_sas (the driver actually reduces the allocation size until
  it succeeds)"
Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: Revert "target: iscsi: Wait for all commands to finish before freeing a session"
  scsi: Revert "RDMA/isert: Fix a recently introduced regression related to logout"
  scsi: megaraid_sas: silence a warning
  scsi: Revert "target/core: Inline transport_lun_remove_cmd()"

Merge tag 'hwmon-for-v5.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging

Pull hwmon fixes from Guenter Roeck:

 - Fix crash in w83627ehf driver seen with W83627DHG-P

 - Fix lockdep splat in acpi_power_meter driver

 - Fix xdpe12284 documentation Sphinx warnings

* tag 'hwmon-for-v5.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (w83627ehf) Fix crash seen with W83627DHG-P
  hwmon: (acpi_power_meter) Fix lockdep splat
  Documentation/hwmon: fix xdpe12284 Sphinx warnings

Pull devicetree fixes deom Rob Herring:
 "A handful of fixes in DT bindings for MDIO bus, Allwinner CSI, OMAP
  HSMMC, and Tegra124 EMC"

* tag 'devicetree-fixes-for-5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
  dt-bindings: media: csi: Fix clocks description
  dt-bindings: media: csi: Add interconnects properties
  dt-bindings: net: mdio: remove compatible string from example
  dt-bindings: memory-controller: Update example for Tegra124 EMC
  dt-bindings: mmc: omap-hsmmc: Fix SDIO interrupt

Pull s390 fixes from Vasily Gorbik:

 - Remove ieee_emulation_warnings sysctl which is a dead code.

 - Avoid triggering rebuild of the kernel during make install.

 - Enable protected virtualization guest support in default configs.

 - Fix cio_ignore seq_file .next function to increase position index.
   And use kobj_to_dev instead of container_of in cio code.

 - Fix storage block address lists to contain absolute addresses in qdio
   code.

 - Few clang warnings and spelling fixes.

* tag 's390-5.6-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/qdio: fill SBALEs with absolute addresses
  s390/qdio: fill SL with absolute addresses
  s390: remove obsolete ieee_emulation_warnings
  s390: make 'install' not depend on vmlinux
  s390/kaslr: Fix casts in get_random
  s390/mm: Explicitly compare PAGE_DEFAULT_KEY against zero in storage_key_init_range
  s390/pkey/zcrypt: spelling s/crytp/crypt/
  s390/cio: use kobj_to_dev() API
  s390/defconfig: enable CONFIG_PROTECTED_VIRTUALIZATION_GUEST
  s390/cio: cio_ignore_proc_seq_next should increase position index

Since commit a3a0e43f ("io_uring: don't enter poll loop if we have
CQEs pending"), if we already events pending, we won't enter poll loop.
In case SETUP_IOPOLL and SETUP_SQPOLL are both enabled, if app has
been terminated and don't reap pending events which are already in cq
ring, and there are some reqs in poll_list, io_sq_thread will enter
__io_iopoll_check(), and find pending events, then return, this loop
will never have a chance to exit.

I have seen this issue in fio stress tests, to fix this issue, let
io_sq_thread call io_iopoll_getevents() with argument 'min' being zero,
and remove __io_iopoll_check().

Fixes: a3a0e43f ("io_uring: don't enter poll loop if we have CQEs pending")
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

When CONFIG_QFMT_V2 is configured as a module, the test in
ext4_feature_set_ok() fails and so mount of filesystems with quota or
project features fails. Fix the test to use IS_ENABLED macro which
works properly even for modules.

Link: https://lore.kernel.org/r/20200221100835.9332-1-jack@suse.cz
Fixes: d65d87a0 ("ext4: improve explanation of a mount failure caused by a misconfigured kernel")
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

I found a NULL pointer dereference in ocfs2_block_group_clear_bits().
The running environment:
	kernel version: 4.19
	A cluster with two nodes, 5 luns mounted on two nodes, and do some
	file operations like dd/fallocate/truncate/rm on every lun with storage
	network disconnection.

The fallocate operation on dm-23-45 caused an null pointer dereference.

The information of NULL pointer dereference as follows:
	[577992.878282] JBD2: Error -5 detected when updating journal superblock for dm-23-45.
	[577992.878290] Aborting journal on device dm-23-45.
	...
	[577992.890778] JBD2: Error -5 detected when updating journal superblock for dm-24-46.
	[577992.890908] __journal_remove_journal_head: freeing b_committed_data
	[577992.890916] (fallocate,88392,52):ocfs2_extend_trans:474 ERROR: status = -30
	[577992.890918] __journal_remove_journal_head: freeing b_committed_data
	[577992.890920] (fallocate,88392,52):ocfs2_rotate_tree_right:2500 ERROR: status = -30
	[577992.890922] __journal_remove_journal_head: freeing b_committed_data
	[577992.890924] (fallocate,88392,52):ocfs2_do_insert_extent:4382 ERROR: status = -30
	[577992.890928] (fallocate,88392,52):ocfs2_insert_extent:4842 ERROR: status = -30
	[577992.890928] __journal_remove_journal_head: freeing b_committed_data
	[577992.890930] (fallocate,88392,52):ocfs2_add_clusters_in_btree:4947 ERROR: status = -30
	[577992.890933] __journal_remove_journal_head: freeing b_committed_data
	[577992.890939] __journal_remove_journal_head: freeing b_committed_data
	[577992.890949] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
	[577992.890950] Mem abort info:
	[577992.890951]   ESR = 0x96000004
	[577992.890952]   Exception class = DABT (current EL), IL = 32 bits
	[577992.890952]   SET = 0, FnV = 0
	[577992.890953]   EA = 0, S1PTW = 0
	[577992.890954] Data abort info:
	[577992.890955]   ISV = 0, ISS = 0x00000004
	[577992.890956]   CM = 0, WnR = 0
	[577992.890958] user pgtable: 4k pages, 48-bit VAs, pgdp = 00000000f8da07a9
	[577992.890960] [0000000000000020] pgd=0000000000000000
	[577992.890964] Internal error: Oops: 96000004 [#1] SMP
	[577992.890965] Process fallocate (pid: 88392, stack limit = 0x00000000013db2fd)
	[577992.890968] CPU: 52 PID: 88392 Comm: fallocate Kdump: loaded Tainted: G        W  OE     4.19.36 #1
	[577992.890969] Hardware name: Huawei TaiShan 2280 V2/BC82AMDD, BIOS 0.98 08/25/2019
	[577992.890971] pstate: 60400009 (nZCv daif +PAN -UAO)
	[577992.891054] pc : _ocfs2_free_suballoc_bits+0x63c/0x968 [ocfs2]
	[577992.891082] lr : _ocfs2_free_suballoc_bits+0x618/0x968 [ocfs2]
	[577992.891084] sp : ffff0000c8e2b810
	[577992.891085] x29: ffff0000c8e2b820 x28: 0000000000000000
	[577992.891087] x27: 00000000000006f3 x26: ffffa07957b02e70
	[577992.891089] x25: ffff807c59d50000 x24: 00000000000006f2
	[577992.891091] x23: 0000000000000001 x22: ffff807bd39abc30
	[577992.891093] x21: ffff0000811d9000 x20: ffffa07535d6a000
	[577992.891097] x19: ffff000001681638 x18: ffffffffffffffff
	[577992.891098] x17: 0000000000000000 x16: ffff000080a03df0
	[577992.891100] x15: ffff0000811d9708 x14: 203d207375746174
	[577992.891101] x13: 73203a524f525245 x12: 20373439343a6565
	[577992.891103] x11: 0000000000000038 x10: 0101010101010101
	[577992.891106] x9 : ffffa07c68a85d70 x8 : 7f7f7f7f7f7f7f7f
	[577992.891109] x7 : 0000000000000000 x6 : 0000000000000080
	[577992.891110] x5 : 0000000000000000 x4 : 0000000000000002
	[577992.891112] x3 : ffff000001713390 x2 : 2ff90f88b1c22f00
	[577992.891114] x1 : ffff807bd39abc30 x0 : 0000000000000000
	[577992.891116] Call trace:
	[577992.891139]  _ocfs2_free_suballoc_bits+0x63c/0x968 [ocfs2]
	[577992.891162]  _ocfs2_free_clusters+0x100/0x290 [ocfs2]
	[577992.891185]  ocfs2_free_clusters+0x50/0x68 [ocfs2]
	[577992.891206]  ocfs2_add_clusters_in_btree+0x198/0x5e0 [ocfs2]
	[577992.891227]  ocfs2_add_inode_data+0x94/0xc8 [ocfs2]
	[577992.891248]  ocfs2_extend_allocation+0x1bc/0x7a8 [ocfs2]
	[577992.891269]  ocfs2_allocate_extents+0x14c/0x338 [ocfs2]
	[577992.891290]  __ocfs2_change_file_space+0x3f8/0x610 [ocfs2]
	[577992.891309]  ocfs2_fallocate+0xe4/0x128 [ocfs2]
	[577992.891316]  vfs_fallocate+0x11c/0x250
	[577992.891317]  ksys_fallocate+0x54/0x88
	[577992.891319]  __arm64_sys_fallocate+0x28/0x38
	[577992.891323]  el0_svc_common+0x78/0x130
	[577992.891325]  el0_svc_handler+0x38/0x78
	[577992.891327]  el0_svc+0x8/0xc

My analysis process as follows:
ocfs2_fallocate
  __ocfs2_change_file_space
    ocfs2_allocate_extents
      ocfs2_extend_allocation
        ocfs2_add_inode_data
          ocfs2_add_clusters_in_btree
            ocfs2_insert_extent
              ocfs2_do_insert_extent
                ocfs2_rotate_tree_right
                  ocfs2_extend_rotate_transaction
                    ocfs2_extend_trans
                      jbd2_journal_restart
                        jbd2__journal_restart
                          /* handle->h_transaction is NULL,
                           * is_handle_aborted(handle) is true
                           */
                          handle->h_transaction = NULL;
                          start_this_handle
                            return -EROFS;
            ocfs2_free_clusters
              _ocfs2_free_clusters
                _ocfs2_free_suballoc_bits
                  ocfs2_block_group_clear_bits
                    ocfs2_journal_access_gd
                      __ocfs2_journal_access
                        jbd2_journal_get_undo_access
                          /* I think jbd2_write_access_granted() will
                           * return true, because do_get_write_access()
                           * will return -EROFS.
                           */
                          if (jbd2_write_access_granted(...)) return 0;
                          do_get_write_access
                            /* handle->h_transaction is NULL, it will
                             * return -EROFS here, so do_get_write_access()
                             * was not called.
                             */
                            if (is_handle_aborted(handle)) return -EROFS;
                    /* bh2jh(group_bh) is NULL, caused NULL
                       pointer dereference */
                    undo_bg = (struct ocfs2_group_desc *)
                                bh2jh(group_bh)->b_committed_data;

If handle->h_transaction == NULL, then jbd2_write_access_granted()
does not really guarantee that journal_head will stay around,
not even speaking of its b_committed_data. The bh2jh(group_bh)
can be removed after ocfs2_journal_access_gd() and before call
"bh2jh(group_bh)->b_committed_data". So, we should move
is_handle_aborted() check from do_get_write_access() into
jbd2_journal_get_undo_access() and jbd2_journal_get_write_access()
before the call to jbd2_write_access_granted().

Link: https://lore.kernel.org/r/f72a623f-b3f1-381a-d91d-d22a1c83a336@huawei.comSigned-off-by: Yan Wang <wangyan122@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@kernel.org

If EXT4_EXTENTS_FL is set on an inode while ext4_writepages() is running
on it, the following warning in ext4_add_complete_io() can be hit:

WARNING: CPU: 1 PID: 0 at fs/ext4/page-io.c:234 ext4_put_io_end_defer+0xf0/0x120

Here's a minimal reproducer (not 100% reliable) (root isn't required):

        while true; do
                sync
        done &
        while true; do
                rm -f file
                touch file
                chattr -e file
                echo X >> file
                chattr +e file
        done

The problem is that in ext4_writepages(), ext4_should_dioread_nolock()
(which only returns true on extent-based files) is checked once to set
the number of reserved journal credits, and also again later to select
the flags for ext4_map_blocks() and copy the reserved journal handle to
ext4_io_end::handle.  But if EXT4_EXTENTS_FL is being concurrently set,
the first check can see dioread_nolock disabled while the later one can
see it enabled, causing the reserved handle to unexpectedly be NULL.

Since changing EXT4_EXTENTS_FL is uncommon, and there may be other races
related to doing so as well, fix this by synchronizing changing
EXT4_EXTENTS_FL with ext4_writepages() via the existing
s_writepages_rwsem (previously called s_journal_flag_rwsem).

This was originally reported by syzbot without a reproducer at
https://syzkaller.appspot.com/bug?extid=2202a584a00fffd19fbf,
but now that dioread_nolock is the default I also started seeing this
when running syzkaller locally.

Link: https://lore.kernel.org/r/20200219183047.47417-3-ebiggers@kernel.org
Reported-by: syzbot+2202a584a00fffd19fbf@syzkaller.appspotmail.com
Fixes: 6b523df4 ("ext4: use transaction reservation for extent conversion in ext4_end_io")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@kernel.org

In preparation for making s_journal_flag_rwsem synchronize
ext4_writepages() with changes to both the EXTENTS and JOURNAL_DATA
flags (rather than just JOURNAL_DATA as it does currently), rename it to
s_writepages_rwsem.

Link: https://lore.kernel.org/r/20200219183047.47417-2-ebiggers@kernel.orgSigned-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@kernel.org

During an online resize an array of s_flex_groups structures gets replaced
so it can get enlarged. If there is a concurrent access to the array and
this memory has been reused then this can lead to an invalid memory access.

The s_flex_group array has been converted into an array of pointers rather
than an array of structures. This is to ensure that the information
contained in the structures cannot get out of sync during a resize due to
an accessor updating the value in the old structure after it has been
copied but before the array pointer is updated. Since the structures them-
selves are no longer copied but only the pointers to them this case is
mitigated.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=206443
Link: https://lore.kernel.org/r/20200221053458.730016-4-tytso@mit.eduSigned-off-by: Suraj Jitindar Singh <surajjs@amazon.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

Pull xen fixes from Juergen Gross:
 "Two small fixes for Xen:

   - a fix to avoid warnings with new gcc

   - a fix for incorrectly disabled interrupts when calling
     _cond_resched()"

* tag 'for-linus-5.6-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: Enable interrupts when calling _cond_resched()
  x86/xen: Distribute switch variables for initialization

Pull arm64 fixes from Will Deacon:
 "It's all straightforward apart from the changes to mmap()/mremap() in
  relation to their handling of address arguments from userspace with
  non-zero tag bits in the upper byte.

  The change to brk() is necessary to fix a nasty user-visible
  regression in malloc(), but we tightened up mmap() and mremap() at the
  same time because they also allow the user to create virtual aliases
  by accident. It's much less likely than brk() to matter in practice,
  but enforcing the principle of "don't permit the creation of mappings
  using tagged addresses" leads to a straightforward ABI without having
  to worry about the "but what if a crazy program did foo?" aspect of
  things.

  Summary:

   - Fix regression in malloc() caused by ignored address tags in brk()

   - Add missing brackets around argument to untagged_addr() macro

   - Fix clang build when using binutils assembler

   - Fix silly typo in virtual memory map documentation"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  mm: Avoid creating virtual address aliases in brk()/mmap()/mremap()
  docs: arm64: fix trivial spelling enought to enough in memory.rst
  arm64: memory: Add missing brackets to untagged_addr() macro
  arm64: lse: Fix LSE atomics with LLVM

Pull powerpc fixes from Michael Ellerman:
 "Some more powerpc fixes for 5.6. This is two weeks worth as I was out
  sick last week:

   - Three fixes for the recently added VMAP_STACK on 32-bit.

   - Three fixes related to hugepages on 8xx (32-bit).

   - A fix for a bug in our transactional memory handling that could
     lead to a kernel crash if we saw a page fault during signal
     delivery.

   - A fix for a deadlock in our PCI EEH (Enhanced Error Handling) code.

   - A couple of other minor fixes.

  Thanks to: Christophe Leroy, Erhard F, Frederic Barrat, Gustavo Luiz
  Duarte, Larry Finger, Leonardo Bras, Oliver O'Halloran, Sam Bobroff"

* tag 'powerpc-5.6-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/entry: Fix an #if which should be an #ifdef in entry_32.S
  powerpc/xmon: Fix whitespace handling in getstring()
  powerpc/6xx: Fix power_save_ppc32_restore() with CONFIG_VMAP_STACK
  powerpc/chrp: Fix enter_rtas() with CONFIG_VMAP_STACK
  powerpc/32s: Fix DSI and ISI exceptions for CONFIG_VMAP_STACK
  powerpc/tm: Fix clearing MSR[TS] in current when reclaiming on signal delivery
  powerpc/8xx: Fix clearing of bits 20-23 in ITLB miss
  powerpc/hugetlb: Fix 8M hugepages on 8xx
  powerpc/hugetlb: Fix 512k hugepages on 8xx with 16k page size
  powerpc/eeh: Fix deadlock handling dead PHB

Pull watchdog fixes from Wim Van Sebroeck:

 - mtk_wdt needs RESET_CONTROLLER to build

 - da9062 driver fixes:
     - fix power management ops
     - do not ping the hw during stop()
     - add dependency on I2C

* tag 'linux-watchdog-5.6-rc3' of git://www.linux-watchdog.org/linux-watchdog:
  watchdog: da9062: Add dependency on I2C
  watchdog: da9062: fix power management ops
  watchdog: da9062: do not ping the hw during stop()
  watchdog: fix mtk_wdt.c RESET_CONTROLLER build error

Pull char/misc driver fixes from Greg KH:
 "Here are some small char/misc driver fixes for 5.6-rc3.

  Also included in here are some updates for some documentation files
  that I seem to be maintaining these days.

  The driver fixes are:
   - small fixes for the habanalabs driver
   - fsi driver bugfix

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

* tag 'char-misc-5.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  Documentation/process: Swap out the ambassador for Canonical
  habanalabs: patched cb equals user cb in device memset
  habanalabs: do not halt CoreSight during hard reset
  habanalabs: halt the engines before hard-reset
  MAINTAINERS: remove unnecessary ':' characters
  fsi: aspeed: add unspecified HAS_IOMEM dependency
  COPYING: state that all contributions really are covered by this file
  Documentation/process: Change Microsoft contact for embargoed hardware issues
  embargoed-hardware-issues: drop Amazon contact as the email address now bounces
  Documentation/process: Add Arm contact for embargoed HW issues

Pull staging driver fixes from Greg KH:
 "Here are some small staging driver fixes for 5.6-rc3, along with the
  removal of an unused/unneeded driver as well.

  The android vsoc driver is not needed anymore by anyone, so it was
  removed.

  The other driver fixes are:
   - ashmem bugfixes
   - greybus audio driver bugfix
   - wireless driver bugfixes and tiny cleanups to error paths

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

* tag 'staging-5.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: rtl8723bs: Remove unneeded goto statements
  staging: rtl8188eu: Remove some unneeded goto statements
  staging: rtl8723bs: Fix potential overuse of kernel memory
  staging: rtl8188eu: Fix potential overuse of kernel memory
  staging: rtl8723bs: Fix potential security hole
  staging: rtl8188eu: Fix potential security hole
  staging: greybus: use after free in gb_audio_manager_remove_all()
  staging: android: Delete the 'vsoc' driver
  staging: rtl8723bs: fix copy of overlapping memory
  staging: android: ashmem: Disallow ashmem memory from being remapped
  staging: vt6656: fix sign of rx_dbm to bb_pre_ed_rssi.

Pull tty/serial driver fixes from Greg KH:
 "Here are a number of small tty and serial driver fixes for 5.6-rc3
  that resolve a bunch of reported issues.

  They are:
   - vt selection and ioctl fixes
   - serdev bugfix
   - atmel serial driver fixes
   - qcom serial driver fixes
   - other minor serial driver fixes

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

* tag 'tty-5.6-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  vt: selection, close sel_buffer race
  vt: selection, handle pending signals in paste_selection
  serial: cpm_uart: call cpm_muram_init before registering console
  tty: serial: qcom_geni_serial: Fix RX cancel command failure
  serial: 8250: Check UPF_IRQ_SHARED in advance
  tty: serial: imx: setup the correct sg entry for tx dma
  vt: vt_ioctl: fix race in VT_RESIZEX
  vt: fix scrollback flushing on background consoles
  tty: serial: tegra: Handle RX transfer in PIO mode if DMA wasn't started
  tty/serial: atmel: manage shutdown in case of RS485 or ISO7816 mode
  serdev: ttyport: restore client ops on deregistration
  serial: ar933x_uart: set UART_CS_{RX,TX}_READY_ORIDE