Copyright © 2012 Red Hat, Inc. All rights reserved. Low 2026-08-15T00:00:00 kernel: jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit() 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CWE-191

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.

A flaw was found in the Linux kernel's jbd2 journaling layer. An integer underflow vulnerability in the `jbd2_journal_initialize_fast_commit()` function occurs when validating journal capacity. This underflow can corrupt critical journal metadata, such as `j_last`, `j_fc_first`, and `j_free`, leading to a journal abort. This issue can result in a Denial of Service (DoS) for the affected system.

Red Hat Enterprise Linux 10 Fix deferred kernel Red Hat Enterprise Linux 6 Out of support scope kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Fix deferred kernel Red Hat Enterprise Linux 9 Fix deferred kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-72225 https://nvd.nist.gov/vuln/detail/CVE-2026-72225 https://lore.kernel.org/linux-cve-announce/2026081548-CVE-2026-72225-e76d@gregkh/T