Re: [syzbot] kernel BUG in create_default_group...

[Edward Adam Davis <eadavis@sina.com>]

From: Edward Aadm Davis <eadavis@sina.com>

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 58161ead29e5

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index eda80c2a2d38..d8e74abe3485 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -65,8 +65,24 @@ static void configfs_d_iput(struct dentry * dentry,
 	iput(inode);
 }
 
+static int configfs_d_revalidate(struct inode *dir, const struct qstr *name,
+			 struct dentry *dentry, unsigned int flags)
+{
+	struct inode *inode = d_inode(dentry);
+	struct configfs_dirent * parent_sd = dentry->d_fsdata;
+
+	if (!inode)
+		return -ECHILD;
+
+	if (!configfs_dirent_is_ready(parent_sd))
+		return -ECHILD;
+
+	return 1;
+}
+
 const struct dentry_operations configfs_dentry_ops = {
 	.d_iput		= configfs_d_iput,
+	.d_revalidate   = configfs_d_revalidate,
 };
 
 #ifdef CONFIG_LOCKDEP