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Ye Bin ed7441ffe3 jbd2: fix the inconsistency between checksum and data in memory for journal sb 
[ Upstream commit 6abfe10789 ]

Copying the file system while it is mounted as read-only results in
a mount failure:
[~]# mkfs.ext4 -F /dev/sdc
[~]# mount /dev/sdc -o ro /mnt/test
[~]# dd if=/dev/sdc of=/dev/sda bs=1M
[~]# mount /dev/sda /mnt/test1
[ 1094.849826] JBD2: journal checksum error
[ 1094.850927] EXT4-fs (sda): Could not load journal inode
mount: mount /dev/sda on /mnt/test1 failed: Bad message

The process described above is just an abstracted way I came up with to
reproduce the issue. In the actual scenario, the file system was mounted
read-only and then copied while it was still mounted. It was found that
the mount operation failed. The user intended to verify the data or use
it as a backup, and this action was performed during a version upgrade.
Above issue may happen as follows:
ext4_fill_super
 set_journal_csum_feature_set(sb)
  if (ext4_has_metadata_csum(sb))
   incompat = JBD2_FEATURE_INCOMPAT_CSUM_V3;
  if (test_opt(sb, JOURNAL_CHECKSUM)
   jbd2_journal_set_features(sbi->s_journal, compat, 0, incompat);
    lock_buffer(journal->j_sb_buffer);
    sb->s_feature_incompat  |= cpu_to_be32(incompat);
    //The data in the journal sb was modified, but the checksum was not
      updated, so the data remaining in memory has a mismatch between the
      data and the checksum.
    unlock_buffer(journal->j_sb_buffer);

In this case, the journal sb copied over is in a state where the checksum
and data are inconsistent, so mounting fails.
To solve the above issue, update the checksum in memory after modifying
the journal sb.

Fixes: 4fd5ea43bc ("jbd2: checksum journal superblock")
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-ID: <20251103010123.3753631-1-yebin@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
[ Changed jbd2_superblock_csum(sb) to jbd2_superblock_csum(journal, sb) ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-01-19 13:10:06 +01:00
arch parisc: entry: set W bit for !compat tasks in syscall_restore_rfi() 2026-01-19 13:10:01 +01:00
block block: rate-limit capacity change info log 2026-01-19 13:09:49 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: seqiv - Do not use req->iv after crypto_aead_encrypt 2026-01-19 13:09:55 +01:00
Documentation fs_context: drop the unused lsm_flags member 2026-01-19 13:09:38 +01:00
drivers xhci: dbgtty: fix device unregister 2026-01-19 13:10:05 +01:00
fs
include usb: gadget: udc: fix use-after-free in usb_gadget_state_work 2026-01-19 13:10:05 +01:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:21:45 +02:00
io_uring io_uring: fix filename leak in __io_openat_prep() 2026-01-19 13:09:54 +01:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:05:26 +01:00
kernel tracing: Do not register unsupported perf events 2026-01-19 13:09:53 +01:00
lib idr: fix idr_alloc() returning an ID out of range 2026-01-19 13:10:02 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/damon/tests/core-kunit: handle memory alloc failure from damon_test_aggregate() 2026-01-19 13:10:05 +01:00
net net: nfc: fix deadlock between nfc_unregister_device and rfkill_fop_write 2026-01-19 13:10:03 +01:00
samples samples: mei: Fix building on musl libc 2025-08-28 16:24:07 +02:00
scripts kbuild: Use CRC32 and a 1MiB dictionary for XZ compressed modules 2026-01-19 13:10:05 +01:00
security KEYS: trusted: Fix a memory leak in tpm2_load_cmd 2026-01-19 13:09:48 +01:00
sound ASoC: qcom: qdsp6: q6asm-dai: set 10 ms period and buffer alignment. 2026-01-19 13:09:59 +01:00
tools idr: fix idr_alloc() returning an ID out of range 2026-01-19 13:10:02 +01:00
usr kbuild: hdrcheck: fix cross build with clang 2025-06-27 11:05:22 +01:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-10-22 15:40:41 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:11:10 +02:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS staging: rtl8712: Remove driver using deprecated API wext 2025-12-07 06:09:36 +09:00
Makefile Linux 5.15.197 2025-12-07 06:09:37 +09:00
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.