ocfs2: fix NULL pointer dereference in function ocfs2_abort_trigger()

ocfs2_abort_trigger() use bh->b_assoc_map to get sb.  But there's no
function to set bh->b_assoc_map in ocfs2, it will trigger NULL pointer
dereference while calling this function.  We can get sb from
bh->b_bdev->bd_super instead of b_assoc_map.

[akpm@linux-foundation.org: update comment, per Joseph]
Signed-off-by: joyce.xue <xuejiufei@huawei.com>
Cc: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 74e364ad1b13fd518a0bd4e5aec56d5e8706152f)

Orabug: 24939243

Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index ff531928269ed1d4e1e0f79bfd6335db3cbc3671..0f3931640d948fcafe9209d1c3b9822c1654ebbe 100644 (file)
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -571,9 +571,7 @@ static void ocfs2_abort_trigger(struct jbd2_buffer_trigger_type *triggers,
             (unsigned long)bh,
             (unsigned long long)bh->b_blocknr);
 
-       /* We aren't guaranteed to have the superblock here - but if we
-        * don't, it'll just crash. */
-       ocfs2_error(bh->b_assoc_map->host->i_sb,
+       ocfs2_error(bh->b_bdev->bd_super,
                    "JBD2 has aborted our journal, ocfs2 cannot continue\n");
 }