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 ed35be3fafc6659ce091d0d6e415e144e719bd97..f469982dcb36e4a98ee1f3fa50fef503143318f8 100644 (file)
--- 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;