Re: [syzbot] [ntfs3?] KASAN: slab-use-after-free Read in chrdev_open

[Hillf Danton]

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git  master

--- x/fs/open.c
+++ y/fs/open.c
@@ -906,9 +906,13 @@ static int do_dentry_open(struct file *f
 {
 	static const struct file_operations empty_fops = {};
 	struct inode *inode = f->f_path.dentry->d_inode;
+	struct dentry *d = f->f_path.dentry;
 	int error;
 
+	if (!lockref_get_not_zero(&d->d_lockref))
+		return -ENODEV;
 	path_get(&f->f_path);
+	dput(d);
 	f->f_inode = inode;
 	f->f_mapping = inode->i_mapping;
 	f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
--