Add kerneldocs for ERR_PTR(), PTR_ERR(), PTR_ERR_OR_ZERO(), IS_ERR(),
and IS_ERR_OR_NULL(). Doing so will help convert hundreds of mentions
of them in existing documentation into automatic cross-references.

Also add kerneldocs for IS_ERR_VALUE(). Doing so adds no automatic
cross-references, but this macro has a slightly different use case
than the functionally similar IS_ERR(), and documenting it may be
helpful to readers who encounter it in existing code.

ERR_CAST() already has kerneldocs and has not been touched.
Signed-off-by: James Seo <james@equiv.tech>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230509175543.2065835-3-james@equiv.tech

Fixes the following error in the docs build that occurs with recent
versions of Sphinx when parsing kerneldocs for a function with the
'__force' macro in its signature:

  ./include/linux/err.h:51: WARNING: Error in declarator or parameters
  Error in declarator or parameters
  Invalid C declaration: Expected identifier, got keyword: void [error at 35]
    void * ERR_CAST (__force const void *ptr)
    -----------------------------------^

Currently, almost all of the few in-signature occurrences of '__force'
are in the error pointer functions. Of those, ERR_CAST() is the only
one with kerneldocs, but the kerneldocs aren't even being used to
generate documentation. This change will allow all the error pointer
functions to be properly documented.

In addition to '__force', <linux/compiler_types.h> also defines
'__nocast', '__safe', and '__private'. These are not currently used in
any function signatures and do not need to be added to the docs config.
Signed-off-by: James Seo <james@equiv.tech>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230509175543.2065835-2-james@equiv.tech

The descriptions of certain KVM related kernel parameters can be
confusing. They state "Disable ...," which may make people think that
setting them to 1 will disable the associated feature when in fact the
opposite is true.

This commit addresses this issue by revising the descriptions of these
parameters by using "Control..." rather than "Enable/Disable...".
1==enabled or 0==disabled can be communicated by the description of
default value such as "1 (enabled)" or "0 (disabled)".

Also update the description of KVM's default value for kvm-intel.nested
as it is enabled by default.
Signed-off-by: Yan-Jie Wang <yanjiewtw@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230503081530.19956-1-yanjiewtw@gmail.com

to make the page more organized as requested
Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230502015040.329394-1-costa.shul@redhat.com

Information about intel_pstate active mode is added in the doc.
This operation mode could be used to set on the hardware when it's
not activated. Status of the mode could be checked from sysfs file
i.e., /sys/devices/system/cpu/intel_pstate/status.
The information is already available in cpu-freq/intel-pstate.txt
documentation.
Signed-off-by: Natesh Sharma <nsharma@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
[jc: reformatted for width ]
Link: https://lore.kernel.org/r/20230427083706.49882-1-nsharma@redhat.com

Use the :Author: markup instead of making it a chapter heading.
This cleans up the table of contents for this file.

Fixes: 7f46a240 ("[PATCH] ramfs, rootfs, and initramfs docs")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Rob Landley <rob@landley.net>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230508055928.3548-1-rdunlap@infradead.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Several of the sections are missing underlines. This makes the
generated contents have missing entries, so add the underlines.

Fixes: 16c01b20 ("doc/filesystems: more mount cleanups")
Fixes: 9cfcceea ("[PATCH] Complete description of shared subtrees.")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20230508055938.6550-1-rdunlap@infradead.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

* improve the short description of localmodconfig in the step-by-step
  guide while fixing its broken first sentence

* briefly mention immutable Linux distributions

* use '--shallow-exclude=v6.0' throughout the document

* instead of "git reset --hard; git checkout ..." use "git checkout
  --force ..." in the step-by-step guide: this matches the TLDR and is
  one command less to execute. This led to a few small adjustments to
  the text and the flow in the surrounding area.

* fix two thinkos in the section explaining full git clones
Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>
Link: https://lore.kernel.org/r/6f4684b9a5d11d3adb04e0af3cfc60db8b28eeb2.1684140700.git.linux@leemhuis.infoSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Use capital letters in acronyms for CD-ROM, FPGA, and PCMCIA.

Use capital letter in the first word of chapter headings for
Locking, Timers, and "Brief tutorial on CRC computation".
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Moritz Fischer <mdf@kernel.org>
Cc: Wu Hao <hao.wu@intel.com>
Cc: Tom Rix <trix@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Xu Yilun <yilun.xu@intel.com>
Reviewed-by: Phillip Potter <phil@philpotter.co.uk>
Link: https://lore.kernel.org/r/20230516001518.14514-1-rdunlap@infradead.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Pull compute express link fixes from Dan Williams:

 - Fix a compilation issue with DEFINE_STATIC_SRCU() in the unit tests

 - Fix leaking kernel memory to a root-only sysfs attribute

* tag 'cxl-fixes-6.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
  cxl: Add missing return to cdat read error path
  tools/testing/cxl: Use DEFINE_STATIC_SRCU()

Pull parisc architecture fixes from Helge Deller:

 - Fix encoding of swp_entry due to added SWP_EXCLUSIVE flag

 - Include reboot.h to avoid gcc-12 compiler warning

* tag 'parisc-for-6.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Fix encoding of swp_entry due to added SWP_EXCLUSIVE flag
  parisc: kexec: include reboot.h

Pull ARM fixes from Russell King:

 - fix unwinder for uleb128 case

 - fix kernel-doc warnings for HP Jornada 7xx

 - fix unbalanced stack on vfp success path

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 9297/1: vfp: avoid unbalanced stack on 'success' return path
  ARM: 9296/1: HP Jornada 7XX: fix kernel-doc warnings
  ARM: 9295/1: unwind:fix unwind abort for uleb128 case

Pull locking fix from Borislav Petkov:

 - Make sure __down_read_common() is always inlined so that the callers'
   names land in traceevents output and thus the blocked function can be
   identified

* tag 'locking_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rwsem: Add __always_inline annotation to __down_read_common() and inlined callers

Pull perf fixes from Borislav Petkov:

 - Make sure the PEBS buffer is flushed before reprogramming the
   hardware so that the correct record sizes are used

 - Update the sample size for AMD BRS events

 - Fix a confusion with using the same on-stack struct with different
   events in the event processing path

* tag 'perf_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel/ds: Flush PEBS DS when changing PEBS_DATA_CFG
  perf/x86: Fix missing sample size update on AMD BRS
  perf/core: Fix perf_sample_data not properly initialized for different swevents in perf_tp_event()

Pull scheduler fix from Borislav Petkov:

 - Fix a couple of kernel-doc warnings

* tag 'sched_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: fix cid_lock kernel-doc warnings

Pull x86 fix from Borislav Petkov:

 - Add the required PCI IDs so that the generic SMN accesses provided by
   amd_nb.c work for drivers which switch to them. Add a PCI device ID
   to k10temp's table so that latter is loaded on such systems too

* tag 'x86_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hwmon: (k10temp) Add PCI ID for family 19, model 78h
  x86/amd_nb: Add PCI ID for family 19h model 78h

Pull timer fix from Borislav Petkov:

 - Prevent CPU state corruption when an active clockevent broadcast
   device is replaced while the system is already in oneshot mode

* tag 'timers_urgent_for_v6.4_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tick/broadcast: Make broadcast device replacement work correctly

Pull ext4 fixes from Ted Ts'o:
 "Some ext4 bug fixes (mostly to address Syzbot reports)"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: bail out of ext4_xattr_ibody_get() fails for any reason
  ext4: add bounds checking in get_max_inline_xattr_value_size()
  ext4: add indication of ro vs r/w mounts in the mount message
  ext4: fix deadlock when converting an inline directory in nojournal mode
  ext4: improve error recovery code paths in __ext4_remount()
  ext4: improve error handling from ext4_dirhash()
  ext4: don't clear SB_RDONLY when remounting r/w until quota is re-enabled
  ext4: check iomap type only if ext4_iomap_begin() does not fail
  ext4: avoid a potential slab-out-of-bounds in ext4_group_desc_csum
  ext4: fix data races when using cached status extents
  ext4: avoid deadlock in fs reclaim with page writeback
  ext4: fix invalid free tracking in ext4_xattr_move_to_block()
  ext4: remove a BUG_ON in ext4_mb_release_group_pa()
  ext4: allow ext4_get_group_info() to fail
  ext4: fix lockdep warning when enabling MMP
  ext4: fix WARNING in mb_find_extent

Pull fbdev fixes from Helge Deller:

 - use after free fix in imsttfb (Zheng Wang)

 - fix error handling in arcfb (Zongjie Li)

 - lots of whitespace cleanups (Thomas Zimmermann)

 - add 1920x1080 modedb entry (me)

* tag 'fbdev-for-6.4-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev:
  fbdev: stifb: Fix info entry in sti_struct on error path
  fbdev: modedb: Add 1920x1080 at 60 Hz video mode
  fbdev: imsttfb: Fix use after free bug in imsttfb_probe
  fbdev: vfb: Remove trailing whitespaces
  fbdev: valkyriefb: Remove trailing whitespaces
  fbdev: stifb: Remove trailing whitespaces
  fbdev: sa1100fb: Remove trailing whitespaces
  fbdev: platinumfb: Remove trailing whitespaces
  fbdev: p9100: Remove trailing whitespaces
  fbdev: maxinefb: Remove trailing whitespaces
  fbdev: macfb: Remove trailing whitespaces
  fbdev: hpfb: Remove trailing whitespaces
  fbdev: hgafb: Remove trailing whitespaces
  fbdev: g364fb: Remove trailing whitespaces
  fbdev: controlfb: Remove trailing whitespaces
  fbdev: cg14: Remove trailing whitespaces
  fbdev: atmel_lcdfb: Remove trailing whitespaces
  fbdev: 68328fb: Remove trailing whitespaces
  fbdev: arcfb: Fix error handling in arcfb_probe()

Pull SCSI fix from James Bottomley:
 "A single small fix for the UFS driver to fix a power management
  failure"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: ufs: core: Fix I/O hang that occurs when BKOPS fails in W-LUN suspend

Fix the __swp_offset() and __swp_entry() macros due to commit 6d239fc7
("parisc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE") which introduced the
SWP_EXCLUSIVE flag by reusing the _PAGE_ACCESSED flag.
Reported-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Tested-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: 6d239fc7 ("parisc/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE")
Cc: <stable@vger.kernel.org> # v6.3+

In ext4_update_inline_data(), if ext4_xattr_ibody_get() fails for any
reason, it's best if we just fail as opposed to stumbling on,
especially if the failure is EFSCORRUPTED.

Cc: stable@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Normally the extended attributes in the inode body would have been
checked when the inode is first opened, but if someone is writing to
the block device while the file system is mounted, it's possible for
the inode table to get corrupted.  Add bounds checking to avoid
reading beyond the end of allocated memory if this happens.

Reported-by: syzbot+1966db24521e5f6e23f7@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=1966db24521e5f6e23f7
Cc: stable@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Whether the file system is mounted read-only or read/write is more
important than the quota mode, which we are already printing.  Add the
ro vs r/w indication since this can be helpful in debugging problems
from the console log.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

In no journal mode, ext4_finish_convert_inline_dir() can self-deadlock
by calling ext4_handle_dirty_dirblock() when it already has taken the
directory lock.  There is a similar self-deadlock in
ext4_incvert_inline_data_nolock() for data files which we'll fix at
the same time.

A simple reproducer demonstrating the problem:

    mke2fs -Fq -t ext2 -O inline_data -b 4k /dev/vdc 64
    mount -t ext4 -o dirsync /dev/vdc /vdc
    cd /vdc
    mkdir file0
    cd file0
    touch file0
    touch file1
    attr -s BurnSpaceInEA -V abcde .
    touch supercalifragilisticexpialidocious

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230507021608.1290720-1-tytso@mit.edu
Reported-by: syzbot+91dccab7c64e2850a4e5@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=ba84cc80a9491d65416bc7877e1650c87530fe8aSigned-off-by: Theodore Ts'o <tytso@mit.edu>

If there are failures while changing the mount options in
__ext4_remount(), we need to restore the old mount options.

This commit fixes two problem.  The first is there is a chance that we
will free the old quota file names before a potential failure leading
to a use-after-free.  The second problem addressed in this commit is
if there is a failed read/write to read-only transition, if the quota
has already been suspended, we need to renable quota handling.

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230506142419.984260-2-tytso@mit.eduSigned-off-by: Theodore Ts'o <tytso@mit.edu>

The ext4_dirhash() will *almost* never fail, especially when the hash
tree feature was first introduced.  However, with the addition of
support of encrypted, casefolded file names, that function can most
certainly fail today.

So make sure the callers of ext4_dirhash() properly check for
failures, and reflect the errors back up to their callers.

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230506142419.984260-1-tytso@mit.edu
Reported-by: syzbot+394aa8a792cb99dbc837@syzkaller.appspotmail.com
Reported-by: syzbot+344aaa8697ebd232bfc8@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=db56459ea4ac4a676ae4b4678f633e55da005a9bSigned-off-by: Theodore Ts'o <tytso@mit.edu>

When a file system currently mounted read/only is remounted
read/write, if we clear the SB_RDONLY flag too early, before the quota
is initialized, and there is another process/thread constantly
attempting to create a directory, it's possible to trigger the

	WARN_ON_ONCE(dquot_initialize_needed(inode));

in ext4_xattr_block_set(), with the following stack trace:

   WARNING: CPU: 0 PID: 5338 at fs/ext4/xattr.c:2141 ext4_xattr_block_set+0x2ef2/0x3680
   RIP: 0010:ext4_xattr_block_set+0x2ef2/0x3680 fs/ext4/xattr.c:2141
   Call Trace:
    ext4_xattr_set_handle+0xcd4/0x15c0 fs/ext4/xattr.c:2458
    ext4_initxattrs+0xa3/0x110 fs/ext4/xattr_security.c:44
    security_inode_init_security+0x2df/0x3f0 security/security.c:1147
    __ext4_new_inode+0x347e/0x43d0 fs/ext4/ialloc.c:1324
    ext4_mkdir+0x425/0xce0 fs/ext4/namei.c:2992
    vfs_mkdir+0x29d/0x450 fs/namei.c:4038
    do_mkdirat+0x264/0x520 fs/namei.c:4061
    __do_sys_mkdirat fs/namei.c:4076 [inline]
    __se_sys_mkdirat fs/namei.c:4074 [inline]
    __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4074

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230506142419.984260-1-tytso@mit.edu
Reported-by: syzbot+6385d7d3065524c5ca6d@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=6513f6cb5cd6b5fc9f37e3bb70d273b94be9c34cSigned-off-by: Theodore Ts'o <tytso@mit.edu>

When ext4_iomap_overwrite_begin() calls ext4_iomap_begin() map blocks may
fail for some reason (e.g. memory allocation failure, bare disk write), and
later because "iomap->type ! = IOMAP_MAPPED" triggers WARN_ON(). When ext4
iomap_begin() returns an error, it is normal that the type of iomap->type
may not match the expectation. Therefore, we only determine if iomap->type
is as expected when ext4_iomap_begin() is executed successfully.

Cc: stable@kernel.org
Reported-by: syzbot+08106c4b7d60702dbc14@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/00000000000015760b05f9b4eee9@google.comSigned-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230505132429.714648-1-libaokun1@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

When modifying the block device while it is mounted by the filesystem,
syzbot reported the following:

BUG: KASAN: slab-out-of-bounds in crc16+0x206/0x280 lib/crc16.c:58
Read of size 1 at addr ffff888075f5c0a8 by task syz-executor.2/15586

CPU: 1 PID: 15586 Comm: syz-executor.2 Not tainted 6.2.0-rc5-syzkaller-00205-gc9661827 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106
 print_address_description+0x74/0x340 mm/kasan/report.c:306
 print_report+0x107/0x1f0 mm/kasan/report.c:417
 kasan_report+0xcd/0x100 mm/kasan/report.c:517
 crc16+0x206/0x280 lib/crc16.c:58
 ext4_group_desc_csum+0x81b/0xb20 fs/ext4/super.c:3187
 ext4_group_desc_csum_set+0x195/0x230 fs/ext4/super.c:3210
 ext4_mb_clear_bb fs/ext4/mballoc.c:6027 [inline]
 ext4_free_blocks+0x191a/0x2810 fs/ext4/mballoc.c:6173
 ext4_remove_blocks fs/ext4/extents.c:2527 [inline]
 ext4_ext_rm_leaf fs/ext4/extents.c:2710 [inline]
 ext4_ext_remove_space+0x24ef/0x46a0 fs/ext4/extents.c:2958
 ext4_ext_truncate+0x177/0x220 fs/ext4/extents.c:4416
 ext4_truncate+0xa6a/0xea0 fs/ext4/inode.c:4342
 ext4_setattr+0x10c8/0x1930 fs/ext4/inode.c:5622
 notify_change+0xe50/0x1100 fs/attr.c:482
 do_truncate+0x200/0x2f0 fs/open.c:65
 handle_truncate fs/namei.c:3216 [inline]
 do_open fs/namei.c:3561 [inline]
 path_openat+0x272b/0x2dd0 fs/namei.c:3714
 do_filp_open+0x264/0x4f0 fs/namei.c:3741
 do_sys_openat2+0x124/0x4e0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_creat fs/open.c:1402 [inline]
 __se_sys_creat fs/open.c:1396 [inline]
 __x64_sys_creat+0x11f/0x160 fs/open.c:1396
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f72f8a8c0c9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f72f97e3168 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007f72f8bac050 RCX: 00007f72f8a8c0c9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000280
RBP: 00007f72f8ae7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd165348bf R14: 00007f72f97e3300 R15: 0000000000022000

Replace
	le16_to_cpu(sbi->s_es->s_desc_size)
with
	sbi->s_desc_size

It reduces ext4's compiled text size, and makes the code more efficient
(we remove an extra indirect reference and a potential byte
swap on big endian systems), and there is no downside. It also avoids the
potential KASAN / syzkaller failure, as a bonus.

Reported-by: syzbot+fc51227e7100c9294894@syzkaller.appspotmail.com
Reported-by: syzbot+8785e41224a3afd04321@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=70d28d11ab14bd7938f3e088365252aa923cff42
Link: https://syzkaller.appspot.com/bug?id=b85721b38583ecc6b5e72ff524c67302abbc30f3
Link: https://lore.kernel.org/all/000000000000ece18705f3b20934@google.com/
Fixes: 717d50e4 ("Ext4: Uninitialized Block Groups")
Cc: stable@vger.kernel.org
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://lore.kernel.org/r/20230504121525.3275886-1-tudor.ambarus@linaro.orgSigned-off-by: Theodore Ts'o <tytso@mit.edu>

When using cached extent stored in extent status tree in tree->cache_es
another process holding ei->i_es_lock for reading can be racing with us
setting new value of tree->cache_es. If the compiler would decide to
refetch tree->cache_es at an unfortunate moment, it could result in a
bogus in_range() check. Fix the possible race by using READ_ONCE() when
using tree->cache_es only under ei->i_es_lock for reading.

Cc: stable@kernel.org
Reported-by: syzbot+4a03518df1e31b537066@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/000000000000d3b33905fa0fd4a6@google.comSuggested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230504125524.10802-1-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

Ext4 has a filesystem wide lock protecting ext4_writepages() calls to
avoid races with switching of journalled data flag or inode format. This
lock can however cause a deadlock like:

CPU0                            CPU1

ext4_writepages()
  percpu_down_read(sbi->s_writepages_rwsem);
                                ext4_change_inode_journal_flag()
                                  percpu_down_write(sbi->s_writepages_rwsem);
                                    - blocks, all readers block from now on
  ext4_do_writepages()
    ext4_init_io_end()
      kmem_cache_zalloc(io_end_cachep, GFP_KERNEL)
        fs_reclaim frees dentry...
          dentry_unlink_inode()
            iput() - last ref =>
              iput_final() - inode dirty =>
                write_inode_now()...
                  ext4_writepages() tries to acquire sbi->s_writepages_rwsem
                    and blocks forever

Make sure we cannot recurse into filesystem reclaim from writeback code
to avoid the deadlock.

Reported-by: syzbot+6898da502aef574c5f8a@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/0000000000004c66b405fa108e27@google.com
Fixes: c8585c6f ("ext4: fix races between changing inode journal mode and ext4_writepages")
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230504124723.20205-1-jack@suse.czSigned-off-by: Theodore Ts'o <tytso@mit.edu>

In ext4_xattr_move_to_block(), the value of the extended attribute
which we need to move to an external block may be allocated by
kvmalloc() if the value is stored in an external inode.  So at the end
of the function the code tried to check if this was the case by
testing entry->e_value_inum.

However, at this point, the pointer to the xattr entry is no longer
valid, because it was removed from the original location where it had
been stored.  So we could end up calling kvfree() on a pointer which
was not allocated by kvmalloc(); or we could also potentially leak
memory by not freeing the buffer when it should be freed.  Fix this by
storing whether it should be freed in a separate variable.

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230430160426.581366-1-tytso@mit.edu
Link: https://syzkaller.appspot.com/bug?id=5c2aee8256e30b55ccf57312c16d88417adbd5e1
Link: https://syzkaller.appspot.com/bug?id=41a6b5d4917c0412eb3b3c3c604965bed7d7420b
Reported-by: syzbot+64b645917ce07d89bde5@syzkaller.appspotmail.com
Reported-by: syzbot+0d042627c4f2ad332195@syzkaller.appspotmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

If a malicious fuzzer overwrites the ext4 superblock while it is
mounted such that the s_first_data_block is set to a very large
number, the calculation of the block group can underflow, and trigger
a BUG_ON check.  Change this to be an ext4_warning so that we don't
crash the kernel.

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230430154311.579720-3-tytso@mit.edu
Reported-by: syzbot+e2efa3efc15a1c9e95c3@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=69b28112e098b070f639efb356393af3ffec4220Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Previously, ext4_get_group_info() would treat an invalid group number
as BUG(), since in theory it should never happen.  However, if a
malicious attaker (or fuzzer) modifies the superblock via the block
device while it is the file system is mounted, it is possible for
s_first_data_block to get set to a very large number.  In that case,
when calculating the block group of some block number (such as the
starting block of a preallocation region), could result in an
underflow and very large block group number.  Then the BUG_ON check in
ext4_get_group_info() would fire, resutling in a denial of service
attack that can be triggered by root or someone with write access to
the block device.

For a quality of implementation perspective, it's best that even if
the system administrator does something that they shouldn't, that it
will not trigger a BUG.  So instead of BUG'ing, ext4_get_group_info()
will call ext4_error and return NULL.  We also add fallback code in
all of the callers of ext4_get_group_info() that it might NULL.

Also, since ext4_get_group_info() was already borderline to be an
inline function, un-inline it.  The results in a next reduction of the
compiled text size of ext4 by roughly 2k.

Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20230430154311.579720-2-tytso@mit.edu
Reported-by: syzbot+e2efa3efc15a1c9e95c3@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=69b28112e098b070f639efb356393af3ffec4220Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

Pull block fixes from Jens Axboe:
 "Just a few minor fixes for drivers, and a deletion of a file that is
  woefully out-of-date these days"

* tag 'block-6.4-2023-05-13' of git://git.kernel.dk/linux:
  Documentation/block: drop the request.rst file
  ublk: fix command op code check
  block/rnbd: replace REQ_OP_FLUSH with REQ_OP_WRITE
  nbd: Fix debugfs_create_dir error checking

Add a return to the error path when cxl_cdat_read_table() fails. Current
code continues with the table pointer points to freed memory.

Fixes: 7a877c92 ("cxl/pci: Simplify CDAT retrieval error path")
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/168382793506.3510737.4792518576623749076.stgit@djiang5-mobl3Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Starting with commit:

95433f72 ("srcu: Begin offloading srcu_struct fields to srcu_update")

...it is no longer possible to do:

static DEFINE_SRCU(x)

Switch to DEFINE_STATIC_SRCU(x) to fix:

tools/testing/cxl/test/mock.c:22:1: error: duplicate ‘static’
   22 | static DEFINE_SRCU(cxl_mock_srcu);
      | ^~~~~~
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/168392709546.1135523.10424917245934547117.stgit@dwillia2-xfh.jf.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

SYM_FUNC_START_LOCAL_NOALIGN() adds an endbr leading to this layout
(leaving only the last 2 bytes of the address):

  3bff <zen_untrain_ret>:
  3bff:       f3 0f 1e fa             endbr64
  3c03:       f6                      test   $0xcc,%bl

  3c04 <__x86_return_thunk>:
  3c04:       c3                      ret
  3c05:       cc                      int3
  3c06:       0f ae e8                lfence

However, "the RET at __x86_return_thunk must be on a 64 byte boundary,
for alignment within the BTB."

Use SYM_START instead.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>