# CVE-2025-38337: jbd2: fix data-race and null-ptr-deref in jbd2\_journal\_dirty\_metadata()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-07-10 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 4.3

## Description

In the Linux kernel, the following vulnerability has been resolved: jbd2: fix data-race and null-ptr-deref in jbd2_journal_dirty_metadata() Since handle->h_transaction may be a NULL pointer, so we should change it to call is_handle_aborted(handle) first before dereferencing it. And the following data-race was reported in my fuzzer: ================================================================== BUG: KCSAN: data-race in jbd2_journal_dirty_metadata / jbd2_journal_dirty_metadata write to 0xffff888011024104 of 4 bytes by task 10881 on cpu 1: jbd2_journal_dirty_metadata+0x2a5/0x770 fs/jbd2/transaction.c:1556 __ext4_handle_dirty_metadata+0xe7/0x4b0 fs/ext4/ext4_jbd2.c:358 ext4_do_update_inode fs/ext4/inode.c:5220 [inline] ext4_mark_iloc_dirty+0x32c/0xd50 fs/ext4/inode.c:5869 __ext4_mark_inode_dirty+0xe1/0x450 fs/ext4/inode.c:6074 ext4_dirty_inode+0x98/0xc0 fs/ext4/inode.c:6103 .... read to 0xffff888011024104 of 4 bytes by task 10880 on cpu 0: jbd2_journal_dirty_metadata+0xf2/0x770 fs/jbd2/transaction.c:1512 __ext4_handle_dirty_metadata+0xe7/0x4b0 fs/ext4/ext4_jbd2.c:358 ext4_do_update_inode fs/ext4/inode.c:5220 [inline] ext4_mark_iloc_dirty+0x32c/0xd50 fs/ext4/inode.c:5869 __ext4_mark_inode_dirty+0xe1/0x450 fs/ext4/inode.c:6074 ext4_dirty_inode+0x98/0xc0 fs/ext4/inode.c:6103 .... value changed: 0x00000000 -> 0x00000001 ================================================================== This issue is caused by missing data-race annotation for jh->b_modified. Therefore, the missing annotation needs to be added.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
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## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/5c1a34ff5b0bfdfd2f9343aa9b08d25df618bac5
- https://git.kernel.org/stable/c/ec669e5bf409f16e464bfad75f0ba039a45de29a
- https://git.kernel.org/stable/c/43d5e3bb5f1dcd91e30238ea0b59a5f77063f84e
- https://git.kernel.org/stable/c/23361b479f2700c00960d3ae9cdc8ededa762d47
- https://git.kernel.org/stable/c/2e7c64d7a92c031d016f11c8e8cb05131ab7b75a
- https://git.kernel.org/stable/c/f78b38af3540b4875147b7b884ee11a27b3dbf4c
- https://git.kernel.org/stable/c/a377996d714afb8d4d5f4906336f78510039da29
- https://git.kernel.org/stable/c/af98b0157adf6504fade79b3e6cb260c4ff68e37

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