[lvc-project] [PATCH] ocfs2: add chain list sanity check to ocfs2_block_group_alloc()

[Dmitry Antipov]

In 'ocfs2_block_group_alloc()', add an extra check whether the maximum
amount of chain records in 'struct ocfs2_chain_list' matches the value
calculated based on the filesystem block size.

Reported-by: syzbot+77026564530dbc29b854 at syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=77026564530dbc29b854
Signed-off-by: Dmitry Antipov <dmantipov at yandex.ru>
---
 fs/ocfs2/suballoc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 6ac4dcd54588..99eb651d5593 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -671,6 +671,13 @@ static int ocfs2_block_group_alloc(struct ocfs2_super *osb,
 	BUG_ON(ocfs2_is_cluster_bitmap(alloc_inode));
 
 	cl = &fe->id2.i_chain;
+	/* If these two doesn't match, the filesystem is most likely corrupted. */
+	if (le16_to_cpu(cl->cl_count) != ocfs2_chain_recs_per_inode(osb->sb)) {
+		status = -EINVAL;
+		mlog_errno(status);
+		goto bail;
+	}
+
 	status = ocfs2_reserve_clusters_with_limit(osb,
 						   le16_to_cpu(cl->cl_cpg),
 						   max_block, flags, &ac);
-- 
2.51.0