Currently, when KASLR is in effect, we set up the kernel virtual address
space twice: the first time, the KASLR seed is looked up in the device
tree, and the kernel virtual mapping is torn down and recreated again,
after which the relocations are applied a second time. The latter step
means that statically initialized global pointer variables will be reset
to their initial values, and to ensure that BSS variables are not set to
values based on the initial translation, they are cleared again as well.

All of this is needed because we need the command line (taken from the
DT) to tell us whether or not to randomize the virtual address space
before entering the kernel proper. However, this code has expanded
little by little and now creates global state unrelated to the virtual
randomization of the kernel before the mapping is torn down and set up
again, and the BSS cleared for a second time. This has created some
issues in the past, and it would be better to avoid this little dance if
possible.

So instead, let's use the temporary mapping of the device tree, and
execute the bare minimum of code to decide whether or not KASLR should
be enabled, and what the seed is. Only then, create the virtual kernel
mapping, clear BSS, etc and proceed as normal.  This avoids the issues
around inconsistent global state due to BSS being cleared twice, and is
generally more maintainable, as it permits us to defer all the remaining
DT parsing and KASLR initialization to a later time.

This means the relocation fixup code runs only a single time as well,
allowing us to simplify the RELR handling code too, which is not
idempotent and was therefore required to keep track of the offset that
was applied the first time around.

Note that this means we have to clone a pair of FDT library objects, so
that we can control how they are built - we need the stack protector
and other instrumentation disabled so that the code can tolerate being
called this early. Note that only the kernel page tables and the
temporary stack are mapped read-write at this point, which ensures that
the early code does not modify any global state inadvertently.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-21-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

The early KASLR init code runs extremely early, and anything that could
be deferred until later should be. So let's defer the randomization of
the module region until much later - this also simplifies the
arithmetic, given that we no longer have to reason about the link time
vs load time placement of the core kernel explicitly. Also get rid of
the global status variable, and infer the status reported by the
diagnostic print from other KASLR related context.

While at it, get rid of the special case for KASAN without
KASAN_VMALLOC, which never occurs in practice.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-20-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

In order to avoid having to touch memory with the MMU and caches
disabled, and therefore having to invalidate it from the caches
explicitly, just defer storing the value until after the MMU has been
turned on, unless we are giving up with an error.

While at it, move the associated variable definitions into C code.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-19-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Now that we can access the entire kernel image via the ID map, we can
execute the page table population code with the MMU and caches enabled.
The only thing we need to ensure is that translations via TTBR1 remain
disabled while we are updating the page tables the second time around,
in case KASLR wants them to be randomized.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-18-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Create a macro load_ttbr1 to avoid having to repeat the same instruction
sequence 3 times in a subsequent patch. No functional change intended.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-17-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Instead of calling into the kernel to map the FDT into the kernel page
tables before even calling start_kernel(), let's switch to the initial,
temporary mapping of the device tree that has been added to the ID map.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-16-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

We need to access the DT very early to get at the command line and the
KASLR seed, which currently means we rely on some hacks to call into the
kernel before really calling into the kernel, which is undesirable.

So instead, let's create a mapping for the FDT in the initial ID map,
which is feasible now that it has been extended to cover more than a
single page or block, and can be updated in place to remap other output
addresses.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-15-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Formerly, we had to access the RELA and RELR tables via the kernel
mapping that was being relocated, and so deriving the start and end
addresses using ADRP/ADD references was not possible, as the relocation
code runs from the ID map.

Now that we map the entire kernel image via the ID map, we can simplify
this, and just load the entries via the ID map as well.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-14-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

As a first step towards avoiding the need to create, tear down and
recreate the kernel virtual mapping with MMU and caches disabled, start
by expanding the ID map so it covers the page tables as well as all
executable code. This will allow us to populate the page tables with the
MMU and caches on, and call KASLR init code before setting up the
virtual mapping.

Since this ID map is only needed at boot, create it as a temporary set
of page tables, and populate the permanent ID map after enabling the MMU
and caches. While at it, switch to read-only attributes for the where
possible, as writable permissions are only needed for the initial kernel
page tables. Note that on 4k granule configurations, the permanent ID
map will now be reduced to a single page rather than a 2M block mapping.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-13-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

The asm macros used to create the initial ID map and kernel mappings
don't support randomly remapping parts of the address space after it has
been populated. What we can do, however, given that all block or page
mappings are created at the final level, is take a subset of the mapped
range and update its attributes or output address. This will permit us
to make parts of these page tables read-only, or remap a part of it to
cover the device tree.

So add a helper that encapsulates this.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-12-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

In preparation for changing the way we initialize the permanent ID map,
update cpu_replace_ttbr1() so we can use it with the initial ID map as
well.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-11-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

We will be adding an initial ID map that covers the entire kernel image,
so we will pass the actual ID map root table to use to __enable_mmu(),
rather than hard code it.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-10-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Some early boot code runs before the virtual placement of the kernel is
finalized, and we used to go back to the very start and recreate the ID
map along with the page tables describing the virtual kernel mapping,
and this involved setting some global variables with the caches off.

In order to ensure that global state created by the KASLR code is not
corrupted by the cache invalidation that occurs in that case, we needed
to clean those global variables to the PoC explicitly.

This is no longer needed now that the ID map is created only once (and
the associated global variable updates are no longer repeated). So drop
the cache maintenance that is no longer necessary.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20220624150651.1358849-9-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Split off the creation of the ID map page tables, so that we can avoid
running it again unnecessarily when KASLR is in effect (which only
randomizes the virtual placement). This will permit us to drop some
explicit cache maintenance to the PoC which was necessary because the
cache invalidation being performed on some global variables might
otherwise clobber unrelated variables that happen to share a cacheline.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-8-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

In a future patch, we will start using an ID map that covers the entire
image, rather than a single page. This means that we need to deal with
the pathological case of an extended ID map where the kernel image does
not fit neatly inside a single entry at the root level, which means we
will need to create additional table entries and map additional pages
for page tables.

The existing map_memory macro already takes care of most of that, so
let's just extend it to deal with this case as well. While at it, drop
the conditional branch on the value of T0SZ: we don't set the variable
anymore in the entry code, and so we can just let the map_memory macro
deal with the case where the output address exceeds VA_BITS.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-7-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Simplify the macros in head.S that are used to set up the early page
tables, by switching to immediates for the number of bits that are
interpreted as the table index at each level. This makes it much
easier to infer from the instruction stream what is going on, and
reduces the number of instructions emitted substantially.

Note that the extended ID map for cases where no additional level needs
to be configured now uses a compile time size as well, which means that
we interpret up to 10 bits as the table index at the root level (for
52-bit physical addressing), without taking into account whether or not
this is supported on the current system.  However, those bits can only
be set if we are executing the image from an address that exceeds the
48-bit PA range, and are guaranteed to be cleared otherwise, and given
that we are dealing with a mapping in the lower TTBR0 range of the
address space, the result is therefore the same as if we'd mask off only
6 bits.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-6-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

The assignment of idmap_ptrs_per_pgd lacks any cache invalidation, even
though it is updated with the MMU and caches disabled. However, we never
bother to read the value again except in the very next instruction, and
so we can just drop the variable entirely.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20220624150651.1358849-5-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Setting idmap_t0sz involves fiddling with the caches if done with the
MMU off. Since we will be creating an initial ID map with the MMU and
caches off, and the permanent ID map with the MMU and caches on, let's
move this assignment of idmap_t0sz out of the startup code, and replace
it with a macro that simply issues the three instructions needed to
calculate the value wherever it is needed before the MMU is turned on.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-4-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Currently, we only support 52-bit virtual addressing on 64k pages
configurations, and in all other cases, vabits_actual is guaranteed to
equal VA_BITS (== VA_BITS_MIN). So get rid of the variable entirely in
that case.

While at it, move the assignment out of the asm entry code - it has no
need to be there.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-3-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

This variable definition does not need to be in head.S so move it out.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20220624150651.1358849-2-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Pull x86 fixes from Thomas Gleixner:

 - Make RESERVE_BRK() work again with older binutils. The recent
   'simplification' broke that.

 - Make early #VE handling increment RIP when successful.

 - Make the #VE code consistent vs. the RIP adjustments and add
   comments.

 - Handle load_unaligned_zeropad() across page boundaries correctly in
   #VE when the second page is shared.

* tag 'x86-urgent-2022-06-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/tdx: Handle load_unaligned_zeropad() page-cross to a shared page
  x86/tdx: Clarify RIP adjustments in #VE handler
  x86/tdx: Fix early #VE handling
  x86/mm: Fix RESERVE_BRK() for older binutils

Pull build tooling updates from Thomas Gleixner:

 - Remove obsolete CONFIG_X86_SMAP reference from objtool

 - Fix overlapping text section failures in faddr2line for real

 - Remove OBJECT_FILES_NON_STANDARD usage from x86 ftrace and replace it
   with finegrained annotations so objtool can validate that code
   correctly.

* tag 'objtool-urgent-2022-06-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/ftrace: Remove OBJECT_FILES_NON_STANDARD usage
  faddr2line: Fix overlapping text section failures, the sequel
  objtool: Fix obsolete reference to CONFIG_X86_SMAP

Pull scheduler fix from Thomas Gleixner:
 "A single scheduler fix plugging a race between sched_setscheduler()
  and balance_push().

  sched_setscheduler() spliced the balance callbacks accross a lock
  break which makes it possible for an interleaving schedule() to
  observe an empty list"

* tag 'sched-urgent-2022-06-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix balance_push() vs __sched_setscheduler()

Pull lockdep fix from Thomas Gleixner:
 "A RT fix for lockdep.

  lockdep invokes prandom_u32() to create cookies. This worked until
  prandom_u32() was switched to the real random generator, which takes a
  spinlock for extraction, which does not work on RT when invoked from
  atomic contexts.

  lockdep has no requirement for real random numbers and it turns out
  sched_clock() is good enough to create the cookie. That works
  everywhere and is faster"

* tag 'locking-urgent-2022-06-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/lockdep: Use sched_clock() for random numbers

Pull irq fixes from Thomas Gleixner:
 "A set of interrupt subsystem updates:

  Core:

   - Ensure runtime power management for chained interrupts

  Drivers:

   - A collection of OF node refcount fixes

   - Unbreak MIPS uniprocessor builds

   - Fix xilinx interrupt controller Kconfig dependencies

   - Add a missing compatible string to the Uniphier driver"

* tag 'irq-urgent-2022-06-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/loongson-liointc: Use architecture register to get coreid
  irqchip/uniphier-aidet: Add compatible string for NX1 SoC
  dt-bindings: interrupt-controller/uniphier-aidet: Add bindings for NX1 SoC
  irqchip/realtek-rtl: Fix refcount leak in map_interrupts
  irqchip/gic-v3: Fix refcount leak in gic_populate_ppi_partitions
  irqchip/gic-v3: Fix error handling in gic_populate_ppi_partitions
  irqchip/apple-aic: Fix refcount leak in aic_of_ic_init
  irqchip/apple-aic: Fix refcount leak in build_fiq_affinity
  irqchip/gic/realview: Fix refcount leak in realview_gic_of_init
  irqchip/xilinx: Remove microblaze+zynq dependency
  genirq: PM: Use runtime PM for chained interrupts

Merge tag 'char-misc-5.19-rc3-take2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char/misc driver fixes for real from Greg KH:
 "Let's tag the proper branch this time...

  Here are some small char/misc driver fixes for 5.19-rc3 that resolve
  some reported issues.

  They include:

   - mei driver fixes

   - comedi driver fix

   - rtsx build warning fix

   - fsl-mc-bus driver fix

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

This is what the merge in commit f0ec9c65 _should_ have merged, but
Greg fat-fingered the pull request and I got some small changes from
linux-next instead there. Credit to Nathan Chancellor for eagle-eyes.

Link: https://lore.kernel.org/all/Yqywy+Md2AfGDu8v@dev-arch.thelio-3990X/

* tag 'char-misc-5.19-rc3-take2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  bus: fsl-mc-bus: fix KASAN use-after-free in fsl_mc_bus_remove()
  mei: me: add raptor lake point S DID
  mei: hbm: drop capability response on early shutdown
  mei: me: set internal pg flag to off on hardware reset
  misc: rtsx: Fix clang -Wsometimes-uninitialized in rts5261_init_from_hw()
  comedi: vmk80xx: fix expression for tx buffer size

Pull i2c fixes from Wolfram Sang:
 "MAINTAINERS rectifications and a few minor driver fixes"

* tag 'i2c-for-5.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: mediatek: Fix an error handling path in mtk_i2c_probe()
  i2c: designware: Use standard optional ref clock implementation
  MAINTAINERS: core DT include belongs to core
  MAINTAINERS: add include/dt-bindings/i2c to I2C SUBSYSTEM HOST DRIVERS
  i2c: npcm7xx: Add check for platform_driver_register
  MAINTAINERS: Update Synopsys DesignWare I2C to Supported

Pull xfs fixes from Darrick Wong:
 "There's not a whole lot this time around (I'm still on vacation) but
  here are some important fixes for new features merged in -rc1:

   - Fix a bug where inode flag changes would accidentally drop nrext64

   - Fix a race condition when toggling LARP mode"

* tag 'xfs-5.19-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: preserve DIFLAG2_NREXT64 when setting other inode attributes
  xfs: fix variable state usage
  xfs: fix TOCTOU race involving the new logged xattrs control knob

Pull ext4 fixes from Ted Ts'o:
 "Fix a variety of bugs, many of which were found by folks using fuzzing
  or error injection.

  Also fix up how test_dummy_encryption mount option is handled for the
  new mount API.

  Finally, fix/cleanup a number of comments and ext4 Documentation
  files"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix a doubled word "need" in a comment
  ext4: add reserved GDT blocks check
  ext4: make variable "count" signed
  ext4: correct the judgment of BUG in ext4_mb_normalize_request
  ext4: fix bug_on ext4_mb_use_inode_pa
  ext4: fix up test_dummy_encryption handling for new mount API
  ext4: use kmemdup() to replace kmalloc + memcpy
  ext4: fix super block checksum incorrect after mount
  ext4: improve write performance with disabled delalloc
  ext4: fix warning when submitting superblock in ext4_commit_super()
  ext4, doc: remove unnecessary escaping
  ext4: fix incorrect comment in ext4_bio_write_page()
  fs: fix jbd2_journal_try_to_free_buffers() kernel-doc comment

Pull cifs client fixes from Steve French:
 "Two cifs debugging improvements - one found to deal with debugging a
  multichannel problem and one for a recent fallocate issue

  This does include the two larger multichannel reconnect (dynamically
  adjusting interfaces on reconnect) patches, because we recently found
  an additional problem with multichannel to one server type that I want
  to include at the same time"

* tag '5.19-rc2-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: when a channel is not found for server, log its connection id
  smb3: add trace point for SMB2_set_eof

Signed-off-by: Xiang wangx <wangxiang@cdjrlc.com>
Link: https://lore.kernel.org/r/20220605091503.12513-1-wangxiang@cdjrlc.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

We capture a NULL pointer issue when resizing a corrupt ext4 image which
is freshly clear resize_inode feature (not run e2fsck). It could be
simply reproduced by following steps. The problem is because of the
resize_inode feature was cleared, and it will convert the filesystem to
meta_bg mode in ext4_resize_fs(), but the es->s_reserved_gdt_blocks was
not reduced to zero, so could we mistakenly call reserve_backup_gdb()
and passing an uninitialized resize_inode to it when adding new group
descriptors.

 mkfs.ext4 /dev/sda 3G
 tune2fs -O ^resize_inode /dev/sda #forget to run requested e2fsck
 mount /dev/sda /mnt
 resize2fs /dev/sda 8G

 ========
 BUG: kernel NULL pointer dereference, address: 0000000000000028
 CPU: 19 PID: 3243 Comm: resize2fs Not tainted 5.18.0-rc7-00001-gfde086c5ebfd #748
 ...
 RIP: 0010:ext4_flex_group_add+0xe08/0x2570
 ...
 Call Trace:
  <TASK>
  ext4_resize_fs+0xbec/0x1660
  __ext4_ioctl+0x1749/0x24e0
  ext4_ioctl+0x12/0x20
  __x64_sys_ioctl+0xa6/0x110
  do_syscall_64+0x3b/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xae
 RIP: 0033:0x7f2dd739617b
 ========

The fix is simple, add a check in ext4_resize_begin() to make sure that
the es->s_reserved_gdt_blocks is zero when the resize_inode feature is
disabled.

Cc: stable@kernel.org
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220601092717.763694-1-yi.zhang@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Since dx_make_map() may return -EFSCORRUPTED now, so change "count" to
be a signed integer so we can correctly check for an error code returned
by dx_make_map().

Fixes: 46c116b9 ("ext4: verify dir block before splitting it")
Cc: stable@kernel.org
Signed-off-by: Ding Xiang <dingxiang@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20220530100047.537598-1-dingxiang@cmss.chinamobile.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

ext4_mb_normalize_request() can move logical start of allocated blocks
to reduce fragmentation and better utilize preallocation. However logical
block requested as a start of allocation (ac->ac_o_ex.fe_logical) should
always be covered by allocated blocks so we should check that by
modifying and to or in the assertion.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220528110017.354175-3-libaokun1@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Hulk Robot reported a BUG_ON:
==================================================================
kernel BUG at fs/ext4/mballoc.c:3211!
[...]
RIP: 0010:ext4_mb_mark_diskspace_used.cold+0x85/0x136f
[...]
Call Trace:
 ext4_mb_new_blocks+0x9df/0x5d30
 ext4_ext_map_blocks+0x1803/0x4d80
 ext4_map_blocks+0x3a4/0x1a10
 ext4_writepages+0x126d/0x2c30
 do_writepages+0x7f/0x1b0
 __filemap_fdatawrite_range+0x285/0x3b0
 file_write_and_wait_range+0xb1/0x140
 ext4_sync_file+0x1aa/0xca0
 vfs_fsync_range+0xfb/0x260
 do_fsync+0x48/0xa0
[...]
==================================================================

Above issue may happen as follows:
-------------------------------------
do_fsync
 vfs_fsync_range
  ext4_sync_file
   file_write_and_wait_range
    __filemap_fdatawrite_range
     do_writepages
      ext4_writepages
       mpage_map_and_submit_extent
        mpage_map_one_extent
         ext4_map_blocks
          ext4_mb_new_blocks
           ext4_mb_normalize_request
            >>> start + size <= ac->ac_o_ex.fe_logical
           ext4_mb_regular_allocator
            ext4_mb_simple_scan_group
             ext4_mb_use_best_found
              ext4_mb_new_preallocation
               ext4_mb_new_inode_pa
                ext4_mb_use_inode_pa
                 >>> set ac->ac_b_ex.fe_len <= 0
           ext4_mb_mark_diskspace_used
            >>> BUG_ON(ac->ac_b_ex.fe_len <= 0);

we can easily reproduce this problem with the following commands:
	`fallocate -l100M disk`
	`mkfs.ext4 -b 1024 -g 256 disk`
	`mount disk /mnt`
	`fsstress -d /mnt -l 0 -n 1000 -p 1`

The size must be smaller than or equal to EXT4_BLOCKS_PER_GROUP.
Therefore, "start + size <= ac->ac_o_ex.fe_logical" may occur
when the size is truncated. So start should be the start position of
the group where ac_o_ex.fe_logical is located after alignment.
In addition, when the value of fe_logical or EXT4_BLOCKS_PER_GROUP
is very large, the value calculated by start_off is more accurate.

Cc: stable@kernel.org
Fixes: cd648b8a ("ext4: trim allocation requests to group size")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220528110017.354175-2-libaokun1@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Since ext4 was converted to the new mount API, the test_dummy_encryption
mount option isn't being handled entirely correctly, because the needed
fscrypt_set_test_dummy_encryption() helper function combines
parsing/checking/applying into one function.  That doesn't work well
with the new mount API, which split these into separate steps.

This was sort of okay anyway, due to the parsing logic that was copied
from fscrypt_set_test_dummy_encryption() into ext4_parse_param(),
combined with an additional check in ext4_check_test_dummy_encryption().
However, these overlooked the case of changing the value of
test_dummy_encryption on remount, which isn't allowed but ext4 wasn't
detecting until ext4_apply_options() when it's too late to fail.
Another bug is that if test_dummy_encryption was specified multiple
times with an argument, memory was leaked.

Fix this up properly by using the new helper functions that allow
splitting up the parse/check/apply steps for test_dummy_encryption.

Fixes: cebe85d5 ("ext4: switch to the new mount api")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20220526040412.173025-1-ebiggers@kernel.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Replace kmalloc + memcpy with kmemdup()
Signed-off-by: Shuqi Zhang <zhangshuqi3@huawei.com>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220525030120.803330-1-zhangshuqi3@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

We got issue as follows:
[home]# mount  /dev/sda  test
EXT4-fs (sda): warning: mounting fs with errors, running e2fsck is recommended
[home]# dmesg
EXT4-fs (sda): warning: mounting fs with errors, running e2fsck is recommended
EXT4-fs (sda): Errors on filesystem, clearing orphan list.
EXT4-fs (sda): recovery complete
EXT4-fs (sda): mounted filesystem with ordered data mode. Quota mode: none.
[home]# debugfs /dev/sda
debugfs 1.46.5 (30-Dec-2021)
Checksum errors in superblock!  Retrying...

Reason is ext4_orphan_cleanup will reset ‘s_last_orphan’ but not update
super block checksum.

To solve above issue, defer update super block checksum after
ext4_orphan_cleanup.
Signed-off-by: Ye Bin <yebin10@huawei.com>
Cc: stable@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220525012904.1604737-1-yebin10@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

cifs_ses_get_chan_index gets the index for a given server pointer.
When a match is not found, we warn about a possible bug.
However, printing details about the non-matching server could be
more useful to debug here.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>