4.19-stable review patch. If anyone has any objections, please let me know.
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From: Julian Sun sunjunchao2870@gmail.com
commit 5784d9fcfd43bd853654bb80c87ef293b9e8e80a upstream.
During the mounting process, if journal_reset() fails because of too short journal, then lead to jbd2_journal_load() fails with NULL j_sb_buffer. Subsequently, ocfs2_journal_shutdown() calls jbd2_journal_flush()->jbd2_cleanup_journal_tail()-> __jbd2_update_log_tail()->jbd2_journal_update_sb_log_tail() ->lock_buffer(journal->j_sb_buffer), resulting in a null-pointer dereference error.
To resolve this issue, we should check the JBD2_LOADED flag to ensure the journal was properly loaded. Additionally, use journal instead of osb->journal directly to simplify the code.
Link: https://syzkaller.appspot.com/bug?extid=05b9b39d8bdfe1a0861f Link: https://lkml.kernel.org/r/20240902030844.422725-1-sunjunchao2870@gmail.com Fixes: f6f50e28f0cb ("jbd2: Fail to load a journal if it is too short") Signed-off-by: Julian Sun sunjunchao2870@gmail.com Reported-by: syzbot+05b9b39d8bdfe1a0861f@syzkaller.appspotmail.com Suggested-by: Joseph Qi joseph.qi@linux.alibaba.com Reviewed-by: Joseph Qi joseph.qi@linux.alibaba.com Cc: Mark Fasheh mark@fasheh.com Cc: Joel Becker jlbec@evilplan.org Cc: Junxiao Bi junxiao.bi@oracle.com Cc: Changwei Ge gechangwei@live.cn Cc: Gang He ghe@suse.com Cc: Jun Piao piaojun@huawei.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ocfs2/journal.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
--- a/fs/ocfs2/journal.c +++ b/fs/ocfs2/journal.c @@ -989,7 +989,7 @@ void ocfs2_journal_shutdown(struct ocfs2 if (!igrab(inode)) BUG();
- num_running_trans = atomic_read(&(osb->journal->j_num_trans)); + num_running_trans = atomic_read(&(journal->j_num_trans)); trace_ocfs2_journal_shutdown(num_running_trans);
/* Do a commit_cache here. It will flush our journal, *and* @@ -1008,9 +1008,10 @@ void ocfs2_journal_shutdown(struct ocfs2 osb->commit_task = NULL; }
- BUG_ON(atomic_read(&(osb->journal->j_num_trans)) != 0); + BUG_ON(atomic_read(&(journal->j_num_trans)) != 0);
- if (ocfs2_mount_local(osb)) { + if (ocfs2_mount_local(osb) && + (journal->j_journal->j_flags & JBD2_LOADED)) { jbd2_journal_lock_updates(journal->j_journal); status = jbd2_journal_flush(journal->j_journal); jbd2_journal_unlock_updates(journal->j_journal);