| Message ID | 20220426182702.716304-1-samjonas@amazon.com |
|---|---|
| State | New |
| Headers | show |
| Series | [4.9-4.19] jbd2: fix use-after-free of transaction_t race | expand |
On Wed, Apr 27, 2022 at 09:31:50AM -0700, Samuel Mendoza-Jonas wrote: > 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/948c2fed518ae739db6a8f7f83f1d58b504f87d0.1644497105.git.ritesh.list@gmail.com > > 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! Thanks for the update, now all dropped from my queue. greg k-h
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); prepare_to_wait(&journal->j_wait_updates, &wait, TASK_UNINTERRUPTIBLE); - 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(); finish_wait(&journal->j_wait_updates, &wait); + 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);