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.
Metrics
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HAffected software
Source: the vendor's advisory (CNA). NVD analysis pending.
No affected versions have been published.
Timeline
- Published
- Aug 15, 2026
- Last modified
- Oct 16, 2026
- NVD status
- Received