CVE-2026-72225

jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()

State: Published
Severity: 7.8 High
Published: Aug 15, 2026
Updated: Oct 16, 2026
Reserved: Aug 9, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()

jbd2_journal_initialize_fast_commit() validates journal capacity by checking (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS). Both j_last and num_fc_blks are unsigned, so when num_fc_blks exceeds j_last the subtraction wraps to a large value, bypassing the bounds check.

The resulting underflow corrupts j_last, j_fc_first, and j_free, leading to journal abort.

Fix by checking num_fc_blks against j_last before the subtraction, returning -EFSCORRUPTED.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before aa90f00932bf572d6ef284c977c2a60b39c13bd6Affected 6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before e144ad0250f77e23e28949587b8b57e40dc3b512Affected 6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before 4b48dcb88bb9117e3d3f051175a9a8b7cff7f8b6Affected 6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before fb9b49618ed7296ebfad62a3835da8945f727001Affected 6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before 4450dcaadf7d4aae8b6e4223b5d6ee4eb77097a9Affected 6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before 78955fdce8ff654e6d33a2fa90882a1e7eb26330Affected 6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before a58fc10adf503969fec2007b5afe8987258046c4Affected 6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before 289a2ca0c9b7eae74f93fc213b0b971669b8683dAffected
LinuxLinux	5.10Affected before 5.10Not affected 5.10.266 through 5.10.Not affected 5.15.212 through 5.15.Not affected 6.1.178 through 6.1.Not affected 6.6.145 through 6.6.Not affected 6.12.97 through 6.12.Not affected 6.18.40 through 6.18.Not affected 7.1.5 through 7.1.*Not affected 7.2 and laterNot affected

Product

Versions

LinuxLinux

6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before aa90f00932bf572d6ef284c977c2a60b39c13bd6Affected
6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before e144ad0250f77e23e28949587b8b57e40dc3b512Affected
6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before 4b48dcb88bb9117e3d3f051175a9a8b7cff7f8b6Affected
6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before fb9b49618ed7296ebfad62a3835da8945f727001Affected
6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before 4450dcaadf7d4aae8b6e4223b5d6ee4eb77097a9Affected
6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before 78955fdce8ff654e6d33a2fa90882a1e7eb26330Affected
6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before a58fc10adf503969fec2007b5afe8987258046c4Affected
6866d7b3f2bb4f011041ba54c98b1584497fe2fd to before 289a2ca0c9b7eae74f93fc213b0b971669b8683dAffected

LinuxLinux

5.10Affected
before 5.10Not affected
5.10.266 through 5.10.*Not affected
5.15.212 through 5.15.*Not affected
6.1.178 through 6.1.*Not affected
6.6.145 through 6.6.*Not affected
6.12.97 through 6.12.*Not affected
6.18.40 through 6.18.*Not affected
7.1.5 through 7.1.*Not affected
7.2 and laterNot affected

References

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