linux-kernel - [PATCH 5.4 175/260] ovl: fix BUG_ON() in may_delete() when called from ovl

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Message-Id: <20210920163937.031727716@linuxfoundation.org>
Date:   Mon, 20 Sep 2021 18:43:13 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, chenying <chenying.kernel@...edance.com>,
        Miklos Szeredi <mszeredi@...hat.com>
Subject: [PATCH 5.4 175/260] ovl: fix BUG_ON() in may_delete() when called from ovl_cleanup()

From: chenying <chenying.kernel@...edance.com>

commit 52d5a0c6bd8a89f460243ed937856354f8f253a3 upstream.

If function ovl_instantiate() returns an error, ovl_cleanup will be called
and try to remove newdentry from wdir, but the newdentry has been moved to
udir at this time.  This will causes BUG_ON(victim->d_parent->d_inode !=
dir) in fs/namei.c:may_delete.

Signed-off-by: chenying <chenying.kernel@...edance.com>
Fixes: 01b39dcc9568 ("ovl: use inode_insert5() to hash a newly created inode")
Link: https://lore.kernel.org/linux-unionfs/e6496a94-a161-dc04-c38a-d2544633acb4@bytedance.com/
Cc: <stable@...r.kernel.org> # v4.18
Signed-off-by: Miklos Szeredi <mszeredi@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/overlayfs/dir.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -513,8 +513,10 @@ static int ovl_create_over_whiteout(stru
 			goto out_cleanup;
 	}
 	err = ovl_instantiate(dentry, inode, newdentry, hardlink);
-	if (err)
-		goto out_cleanup;
+	if (err) {
+		ovl_cleanup(udir, newdentry);
+		dput(newdentry);
+	}
 out_dput:
 	dput(upper);
 out_unlock: