On Tue, Apr 26, 2022 at 11:27:01AM -0700, Samuel Mendoza-Jonas wrote:
From: Ritesh Harjani riteshh@linux.ibm.com
commit cc16eecae687912238ee6efbff71ad31e2bc414e upstream.
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/948c2fed518ae739db6a8f7f83f1d58b504f87d0.164449710... Fixes: 4f98186848707f53 ("jbd2: refactor wait logic for transaction updates into a common function") Cc: stable@kernel.org Reported-and-tested-by: syzbot+afa2ca5171d93e44b348@syzkaller.appspotmail.com Reviewed-by: Jan Kara jack@suse.cz Signed-off-by: Ritesh Harjani riteshh@linux.ibm.com Signed-off-by: Theodore Ts'o tytso@mit.edu [backport to 4.9-4.19 in original jbd2_journal_commit_transaction() location before the refactor in 4f9818684870 "jbd2: refactor wait logic for transaction updates into a common function"] Signed-off-by: Samuel Mendoza-Jonas samjonas@amazon.com Fixes: 1da177e4c3f41524 Cc: stable@kernel.org # 4.9.x - 4.19.x
While marked for 5.17 stable, it looks like this fix also applies to the original location in jbd2_journal_commit_transaction() before it was refactored to use jbd2_journal_wait_updates(). This applies the same change there.
Jan kindly pointed out this was a false alarm: https://lore.kernel.org/all/20220427111726.3wdyxbqoxs7skdzf@quack3.lan/
So the existing patch is fine and these can be ignored!
Cheers, Sam
fs/jbd2/commit.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 97760cb9bcd7..66e776eb5ea7 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -382,6 +382,7 @@ void jbd2_journal_commit_transaction(journal_t *journal) int csum_size = 0; LIST_HEAD(io_bufs); LIST_HEAD(log_bufs);
- DEFINE_WAIT(wait);
if (jbd2_journal_has_csum_v2or3(journal)) csum_size = sizeof(struct jbd2_journal_block_tail); @@ -434,22 +435,25 @@ void jbd2_journal_commit_transaction(journal_t *journal) stats.run.rs_running = jbd2_time_diff(commit_transaction->t_start, stats.run.rs_locked);
- spin_lock(&commit_transaction->t_handle_lock);
- while (atomic_read(&commit_transaction->t_updates)) {
DEFINE_WAIT(wait);
- while (1) {
commit_transaction = journal->j_running_transaction;if (!commit_transaction)break;
spin_lock(&commit_transaction->t_handle_lock);
if (atomic_read(&commit_transaction->t_updates)) {
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);
finish_wait(&journal->j_wait_updates, &wait);break;spin_unlock(&commit_transaction->t_handle_lock);write_unlock(&journal->j_state_lock);schedule();write_lock(&journal->j_state_lock);
- spin_unlock(&commit_transaction->t_handle_lock);
J_ASSERT (atomic_read(&commit_transaction->t_outstanding_credits) <= journal->j_max_transaction_buffers); -- 2.25.1