[PATCH v2] ovl: Filter invalid inodes with missing lookup function

[Vasiliy Kovalev <kovalev@altlinux.org>]

Add a check to the ovl_dentry_weird() function to prevent the
processing of directory inodes that lack the lookup function.
This is important because such inodes can cause errors in overlayfs
when passed to the lowerstack.

Reported-by: syzbot+a8c9d476508bd14a90e5@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=a8c9d476508bd14a90e5
Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Vasiliy Kovalev <kovalev@altlinux.org>
Cc: <stable@vger.kernel.org>
---
 fs/overlayfs/util.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 3bb107471fb42..9aa7493b1e103 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -202,6 +202,9 @@ void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
 
 bool ovl_dentry_weird(struct dentry *dentry)
 {
+	if (!d_can_lookup(dentry) && !d_is_file(dentry) && !d_is_symlink(dentry))
+		return true;
+
 	return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
 				  DCACHE_MANAGE_TRANSIT |
 				  DCACHE_OP_HASH |
-- 
2.33.8