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Chao Yu 115557cc22 f2fs: don't reset unchangable mount option in f2fs_remount() 
commit 458c15dfbc upstream.

syzbot reports a bug as below:

general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN
RIP: 0010:__lock_acquire+0x69/0x2000 kernel/locking/lockdep.c:4942
Call Trace:
 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5691
 __raw_write_lock include/linux/rwlock_api_smp.h:209 [inline]
 _raw_write_lock+0x2e/0x40 kernel/locking/spinlock.c:300
 __drop_extent_tree+0x3ac/0x660 fs/f2fs/extent_cache.c:1100
 f2fs_drop_extent_tree+0x17/0x30 fs/f2fs/extent_cache.c:1116
 f2fs_insert_range+0x2d5/0x3c0 fs/f2fs/file.c:1664
 f2fs_fallocate+0x4e4/0x6d0 fs/f2fs/file.c:1838
 vfs_fallocate+0x54b/0x6b0 fs/open.c:324
 ksys_fallocate fs/open.c:347 [inline]
 __do_sys_fallocate fs/open.c:355 [inline]
 __se_sys_fallocate fs/open.c:353 [inline]
 __x64_sys_fallocate+0xbd/0x100 fs/open.c:353
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The root cause is race condition as below:
- since it tries to remount rw filesystem, so that do_remount won't
call sb_prepare_remount_readonly to block fallocate, there may be race
condition in between remount and fallocate.
- in f2fs_remount(), default_options() will reset mount option to default
one, and then update it based on result of parse_options(), so there is
a hole which race condition can happen.

Thread A			Thread B
- f2fs_fill_super
 - parse_options
  - clear_opt(READ_EXTENT_CACHE)

- f2fs_remount
 - default_options
  - set_opt(READ_EXTENT_CACHE)
				- f2fs_fallocate
				 - f2fs_insert_range
				  - f2fs_drop_extent_tree
				   - __drop_extent_tree
				    - __may_extent_tree
				     - test_opt(READ_EXTENT_CACHE) return true
				    - write_lock(&et->lock) access NULL pointer
 - parse_options
  - clear_opt(READ_EXTENT_CACHE)

Cc: <stable@vger.kernel.org>
Reported-by: syzbot+d015b6c2fbb5c383bf08@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-f2fs-devel/20230522124203.3838360-1-chao@kernel.org
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2023-07-23 13:53:50 +02:00
arch riscv: mm: fix truncation warning on RV32 2023-07-23 13:53:48 +02:00
block blk-crypto: use dynamic lock class for blk_crypto_profile::lock 2023-07-23 13:53:39 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:36:19 +02:00
Documentation fs: Lock moved directories 2023-07-19 16:36:55 +02:00
drivers drm/client: Send hotplug event after registering a client 2023-07-23 13:53:50 +02:00
fs f2fs: don't reset unchangable mount option in f2fs_remount() 2023-07-23 13:53:50 +02:00
include net/sched: make psched_mtu() RTNL-less safe 2023-07-23 13:53:49 +02:00
init kbuild: Fix CFI failures with GCOV 2023-07-19 16:36:23 +02:00
io_uring io_uring: Use io_schedule* in cqring wait 2023-07-19 16:37:03 +02:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel bpf: cpumap: Fix memory leak in cpu_map_update_elem 2023-07-23 13:53:47 +02:00
lib lib: dhry: fix sleeping allocations inside non-preemptable section 2023-07-19 16:36:50 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm shmem: use ramfs_kill_sb() for kill_sb method of ramfs-based tmpfs 2023-07-19 16:36:54 +02:00
net net/sched: sch_qfq: account for stab overhead in qfq_enqueue 2023-07-23 13:53:49 +02:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples samples/bpf: xdp1 and xdp2 reduce XDPBUFSIZE to 60 2023-07-19 16:35:25 +02:00
scripts kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS 2023-07-19 16:37:00 +02:00
security security/integrity: fix pointer to ESL data and its size on pseries 2023-07-23 13:53:34 +02:00
sound ASoC: mediatek: mt8173: Fix snd_soc_component_initialize error path 2023-07-19 16:36:58 +02:00
tools wireguard: netlink: send staged packets when setting initial private key 2023-07-19 16:37:02 +02:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Avoid illegal stage2 mapping on invalid memory slot 2023-06-22 15:14:57 -04:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Ben Dooks 2023-06-19 13:19:35 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Networking fixes for 6.4-rc8, including fixes from ipsec, bpf, 2023-06-22 17:59:51 -07:00
Makefile Linux 6.4.4 2023-07-19 16:37:03 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.