jbd2: fix use after free in jbd2_journal_dirty_metadata()
authorJan Kara <jack@suse.cz>
Mon, 11 Mar 2013 17:24:56 +0000 (13:24 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 28 Mar 2013 19:12:15 +0000 (12:12 -0700)
commitac4f52e0fff3a2b5523655250cc2e7d77ba8c09b
tree94f566e310b0f8eefdbf2237b414b0f03f243760
parent056f8c8c85d53311530fd1940a68a390cc615bde
jbd2: fix use after free in jbd2_journal_dirty_metadata()

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