Re: [PATCH v2] jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()

[Theodore Ts'o]

On Wed, 13 May 2026 17:28:40 +0800, Junrui Luo wrote:
> 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.
> 
> [...]

Applied, thanks!

[1/1] jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()
      commit: 289a2ca0c9b7eae74f93fc213b0b971669b8683d

Best regards,
-- 
Theodore Ts'o <tytso@xxxxxxx>