5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> [ Upstream commit cc16eecae687912238ee6efbff71ad31e2bc414e ] jbd2_journal_wait_updates() is called with j_state_lock held. But if there is a commit in progress, then this transaction might get committed and freed via jbd2_journal_commit_transaction() -> jbd2_journal_free_transaction(), when we release j_state_lock. So check for journal->j_running_transaction everytime we release and acquire j_state_lock to avoid use-after-free issue. Link: https://lore.kernel.org/r/948c2fed518ae739db6a8f7f83f1d58b504f87d0.1644497105.git.ritesh.list@xxxxxxxxx Fixes: 4f98186848707f53 ("jbd2: refactor wait logic for transaction updates into a common function") Cc: stable@xxxxxxxxxx Reported-and-tested-by: syzbot+afa2ca5171d93e44b348@xxxxxxxxxxxxxxxxxxxxxxxxx Reviewed-by: Jan Kara <jack@xxxxxxx> Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Stable-dep-of: 2dfba3bb40ad ("jbd2: correct the end of the journal recovery scan range") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/jbd2/transaction.c | 41 +++++++++++++++++++++++++---------------- 1 file changed, 25 insertions(+), 16 deletions(-) diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index 69aed72c8206d..59292b82d4424 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -842,27 +842,38 @@ EXPORT_SYMBOL(jbd2_journal_restart); */ void jbd2_journal_wait_updates(journal_t *journal) { - transaction_t *commit_transaction = journal->j_running_transaction; + DEFINE_WAIT(wait); - if (!commit_transaction) - return; + while (1) { + /* + * Note that the running transaction can get freed under us if + * this transaction is getting committed in + * jbd2_journal_commit_transaction() -> + * jbd2_journal_free_transaction(). This can only happen when we + * release j_state_lock -> schedule() -> acquire j_state_lock. + * Hence we should everytime retrieve new j_running_transaction + * value (after j_state_lock release acquire cycle), else it may + * lead to use-after-free of old freed transaction. + */ + transaction_t *transaction = journal->j_running_transaction; - spin_lock(&commit_transaction->t_handle_lock); - while (atomic_read(&commit_transaction->t_updates)) { - DEFINE_WAIT(wait); + if (!transaction) + break; + spin_lock(&transaction->t_handle_lock); prepare_to_wait(&journal->j_wait_updates, &wait, - TASK_UNINTERRUPTIBLE); - if (atomic_read(&commit_transaction->t_updates)) { - spin_unlock(&commit_transaction->t_handle_lock); - write_unlock(&journal->j_state_lock); - schedule(); - write_lock(&journal->j_state_lock); - spin_lock(&commit_transaction->t_handle_lock); + TASK_UNINTERRUPTIBLE); + if (!atomic_read(&transaction->t_updates)) { + spin_unlock(&transaction->t_handle_lock); + finish_wait(&journal->j_wait_updates, &wait); + break; } + spin_unlock(&transaction->t_handle_lock); + write_unlock(&journal->j_state_lock); + schedule(); finish_wait(&journal->j_wait_updates, &wait); + write_lock(&journal->j_state_lock); } - spin_unlock(&commit_transaction->t_handle_lock); } /** @@ -877,8 +888,6 @@ void jbd2_journal_wait_updates(journal_t *journal) */ void jbd2_journal_lock_updates(journal_t *journal) { - DEFINE_WAIT(wait); - jbd2_might_wait_for_commit(journal); write_lock(&journal->j_state_lock); -- 2.40.1
