From: Miklos Szeredi <mszeredi@redhat.com>
Date: Fri, 6 Aug 2021 08:03:12 +0000 (+0200)
Subject: ovl: fix uninitialized pointer read in ovl_lookup_real_one()
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=ef2d68ef9a3bff68915e6fdf5b61822bd1f6af4c;p=linux-block.git

ovl: fix uninitialized pointer read in ovl_lookup_real_one()

[ Upstream commit 580c610429b3994e8db24418927747cf28443cde ]

One error path can result in release_dentry_name_snapshot() being called
before "name" was initialized by take_dentry_name_snapshot().

Fix by moving the release_dentry_name_snapshot() to immediately after the
only use.

Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index ed35be3fafc6..f469982dcb36 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -390,6 +390,7 @@ static struct dentry *ovl_lookup_real_one(struct dentry *connected,
 	 */
 	take_dentry_name_snapshot(&name, real);
 	this = lookup_one_len(name.name.name, connected, name.name.len);
+	release_dentry_name_snapshot(&name);
 	err = PTR_ERR(this);
 	if (IS_ERR(this)) {
 		goto fail;
@@ -404,7 +405,6 @@ static struct dentry *ovl_lookup_real_one(struct dentry *connected,
 	}
 
 out:
-	release_dentry_name_snapshot(&name);
 	dput(parent);
 	inode_unlock(dir);
 	return this;