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Chao Yu e2fb24ce37 f2fs: don't reset unchangable mount option in f2fs_remount()
[ Upstream commit 458c15dfbce62c35fefd9ca637b20a051309c9f1 ]

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: Sasha Levin <sashal@kernel.org>
2023-08-11 12:08:26 +02:00
arch powerpc/mm/altmap: Fix altmap boundary check 2023-08-11 12:08:25 +02:00
block blk-mq: Fix stall due to recursive flush plug 2023-08-03 10:23:48 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:21:42 +02:00
Documentation iommu/arm-smmu-v3: Document nesting-related errata 2023-08-11 12:08:09 +02:00
drivers drm/amd/display: skip CLEAR_PAYLOAD_ID_TABLE if device mst_en is 0 2023-08-11 12:08:25 +02:00
fs f2fs: don't reset unchangable mount option in f2fs_remount() 2023-08-11 12:08:26 +02:00
include f2fs: fix to do sanity check on direct node in truncate_dnode() 2023-08-11 12:08:24 +02:00
init x86/mm: Initialize text poking earlier 2023-08-08 20:03:49 +02:00
io_uring io_uring: annotate offset timeout races 2023-08-11 12:08:24 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf, cpumap: Make sure kthread is running before map update returns 2023-08-11 12:08:23 +02:00
lib debugobjects: Recheck debug_objects_enabled before reporting 2023-08-11 12:08:23 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: kmem: fix a NULL pointer dereference in obj_stock_flush_required() 2023-08-11 12:08:23 +02:00
net Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_ready_cb 2023-08-11 12:08:23 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples samples: ftrace: Save required argument registers in sample trampolines 2023-07-23 13:49:44 +02:00
scripts scripts/kallsyms: update the usage in the comment block 2023-07-27 08:50:50 +02:00
security security: keys: Modify mismatched function name 2023-07-27 08:50:43 +02:00
sound ASoC: wm8904: Fill the cache for WM8904_ADC_TEST_0 register 2023-08-03 10:24:16 +02:00
tools selftests/rseq: Play nice with binaries statically linked against glibc 2.35+ 2023-08-11 12:08:26 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-08-03 10:24:08 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.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: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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 smb: move client and server files to common directory fs/smb 2023-06-28 11:12:40 +02:00
Makefile Linux 6.1.44 2023-08-08 20:03:51 +02:00
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.