linux-kernel - [PATCH 4.2.y-ckt 65/98] ovl: fix getcwd() failure after unsuccessful rmdir

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Date:	Tue, 15 Mar 2016 16:30:59 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Rui Wang <rui.y.wang@...el.com>,
	Miklos Szeredi <miklos@...redi.hu>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 65/98] ovl: fix getcwd() failure after unsuccessful rmdir

4.2.8-ckt6 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Rui Wang <rui.y.wang@...el.com>

commit ce9113bbcbf45a57c082d6603b9a9f342be3ef74 upstream.

ovl_remove_upper() should do d_drop() only after it successfully
removes the dir, otherwise a subsequent getcwd() system call will
fail, breaking userspace programs.

This is to fix: https://bugzilla.kernel.org/show_bug.cgi?id=110491

Signed-off-by: Rui Wang <rui.y.wang@...el.com>
Reviewed-by: Konstantin Khlebnikov <koct9i@...il.com>
Signed-off-by: Miklos Szeredi <miklos@...redi.hu>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 fs/overlayfs/dir.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 692ceda..36d6a5b 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -618,7 +618,8 @@ static int ovl_remove_upper(struct dentry *dentry, bool is_dir)
 	 * sole user of this dentry.  Too tricky...  Just unhash for
 	 * now.
 	 */
-	d_drop(dentry);
+	if (!err)
+		d_drop(dentry);
 	mutex_unlock(&dir->i_mutex);
 
 	return err;
-- 
2.7.0