[lvc-project] [PATCH] ocfs2: add extra consistency checks for chain allocator dinodes

[Dmitry Antipov]

When validating chain allocator dinode in 'ocfs2_validate_inode_block()',
add an extra checks whether a) the maximum amount of chain records in
'struct ocfs2_chain_list' matches the value calculated based on the
filesystem block size, and b) the next free slot index is within the
valid range.

Reported-by: syzbot+77026564530dbc29b854 at syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=77026564530dbc29b854
Reported-by: syzbot+5054473a31f78f735416 at syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=5054473a31f78f735416
Suggested-by: Joseph Qi <joseph.qi at linux.alibaba.com>
Signed-off-by: Dmitry Antipov <dmantipov at yandex.ru>
---
note: this is going to replace "ocfs2: introduce chain list sanity check
      with ocfs2_check_chain_list()" because it looks more consistent and
      allows to filter out damaged/inconsistent dinodes earlier (immediately
      after being read).
---
 fs/ocfs2/inode.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index fcc89856ab95..1b6bdd9d7755 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -1503,6 +1503,23 @@ int ocfs2_validate_inode_block(struct super_block *sb,
 		goto bail;
 	}
 
+	if (le32_to_cpu(di->i_flags) & OCFS2_CHAIN_FL) {
+		struct ocfs2_chain_list *cl = &di->id2.i_chain;
+
+		if (le16_to_cpu(cl->cl_count) != ocfs2_chain_recs_per_inode(sb)) {
+			rc = ocfs2_error(sb, "Invalid dinode %llu: chain list count %u\n",
+					 (unsigned long long)bh->b_blocknr,
+					 le16_to_cpu(cl->cl_count));
+			goto bail;
+		}
+		if (le16_to_cpu(cl->cl_next_free_rec) > le16_to_cpu(cl->cl_count)) {
+			rc = ocfs2_error(sb, "Invalid dinode %llu: chain list index %u\n",
+					 (unsigned long long)bh->b_blocknr,
+					 le16_to_cpu(cl->cl_next_free_rec));
+			goto bail;
+		}
+	}
+
 	rc = 0;
 
 bail:
-- 
2.51.0