[ 67/98] jbd2: fix use after free in jbd2_journal_dirty_metadata()

Greg Kroah-Hartman
2013-03-26T23:31:13Z

From: Jan Kara <jack@suse.cz>

commit ad56edad089b56300fd13bb9eeb7d0424d978239 upstream.

jbd2_journal_dirty_metadata() didn't get a reference to journal_head it
was working with. This is OK in most of the cases since the journal head
should be attached to a transaction but in rare occasions when we are
journalling data, __ext4_journalled_writepage() can race with
jbd2_journal_invalidatepage() stripping buffers from a page and thus
journal head can be freed under hands of jbd2_journal_dirty_metadata().

Fix the problem by getting own journal head reference in
jbd2_journal_dirty_metadata() (and also in jbd2_journal_set_triggers()
which can possibly have the same issue).

Reported-by: Zheng Liu <gnehzuil.liu@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/jbd2/transaction.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1047,9 +1047,12 @@ out:
void jbd2_journal_set_triggers(struct buffer_head *bh,
struct jbd2_buffer_trigger_type *type)
{
- struct journal_head *jh = bh2jh(bh);
+ struct journal_head *jh = jbd2_journal_grab_journal_head(bh);

+ if (WARN_ON(!jh))
+ return;
jh->b_triggers = type;
+ jbd2_journal_put_journal_head(jh);
}

void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
@@ -1101,17 +1104,18 @@ int jbd2_journal_dirty_metadata(handle_t
{
transaction_t *transaction = handle->h_transaction;
journal_t *journal = transaction->t_journal;
- struct journal_head *jh = bh2jh(bh);
+ struct journal_head *jh;
int ret = 0;

- jbd_debug(5, "journal_head %p\n", jh);
- JBUFFER_TRACE(jh, "entry");
if (is_handle_aborted(handle))
goto out;
- if (!buffer_jbd(bh)) {
+ jh = jbd2_journal_grab_journal_head(bh);
+ if (!jh) {
ret = -EUCLEAN;
goto out;
}
+ jbd_debug(5, "journal_head %p\n", jh);
+ JBUFFER_TRACE(jh, "entry");

jbd_lock_bh_state(bh);

@@ -1202,6 +1206,7 @@ int jbd2_journal_dirty_metadata(handle_t
spin_unlock(&journal->j_list_lock);
out_unlock_bh:
jbd_unlock_bh_state(bh);
+ jbd2_journal_put_journal_head(jh);
out:
JBUFFER_TRACE(jh, "exit");
WARN_ON(ret); /* All errors are bugs, so dump the stack */