CVE-2023-53526

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

jbd2: check jh->b_transaction before removing it from checkpoint

Following process will corrupt ext4 image: Step 1: jbd2_journal_commit_transaction __jbd2_journal_insert_checkpoint(jh, commit_transaction) // Put jh into trans1->t_checkpoint_list journal->j_checkpoint_transactions = commit_transaction // Put trans1 into journal->j_checkpoint_transactions

Step 2: do_get_write_access test_clear_buffer_dirty(bh) // clear buffer dirty，set jbd dirty __jbd2_journal_file_buffer(jh, transaction) // jh belongs to trans2

Step 3: drop_cache journal_shrink_one_cp_list jbd2_journal_try_remove_checkpoint if (!trylock_buffer(bh)) // lock bh, true if (buffer_dirty(bh)) // buffer is not dirty __jbd2_journal_remove_checkpoint(jh) // remove jh from trans1->t_checkpoint_list

Step 4: jbd2_log_do_checkpoint trans1 = journal->j_checkpoint_transactions // jh is not in trans1->t_checkpoint_list jbd2_cleanup_journal_tail(journal) // trans1 is done

Step 5: Power cut, trans2 is not committed, jh is lost in next mounting.

Fix it by checking jh->b_transaction before remove it from checkpoint.

Affected Software

References

• https://git.kernel.org/stable/c/2298f2589903a8bc03061b54b31fd97985ab6529
• https://git.kernel.org/stable/c/590a809ff743e7bd890ba5fb36bc38e20a36de53
• https://git.kernel.org/stable/c/dbafe636db415299e54d9dfefc1003bda9e71c9d
• https://git.kernel.org/stable/c/ef5fea70e5915afd64182d155e72bfb4f275e1fc