Patch "ovl: fix false positive ESTALE on lookup" has been added to the 4.13-stable tree

Patch "ovl: fix false positive ESTALE on lookup" has been added to the 4.13-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    ovl: fix false positive ESTALE on lookup

to the 4.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ovl-fix-false-positive-estale-on-lookup.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 939ae4efd51c627da270af74ef069db5124cb5b0 Mon Sep 17 00:00:00 2001
From: Amir Goldstein <amir73il@gmail.com>
Date: Mon, 11 Sep 2017 16:30:15 +0300
Subject: ovl: fix false positive ESTALE on lookup

From: Amir Goldstein <amir73il@gmail.com>

commit 939ae4efd51c627da270af74ef069db5124cb5b0 upstream.

Commit b9ac5c274b8c ("ovl: hash overlay non-dir inodes by copy up origin")
verifies that the origin lower inode stored in the overlayfs inode matched
the inode of a copy up origin dentry found by lookup.

There is a false positive result in that check when lower fs does not
support file handles and copy up origin cannot be followed by file handle
at lookup time.

The false negative happens when finding an overlay inode in cache on a
copied up overlay dentry lookup. The overlay inode still 'remembers' the
copy up origin inode, but the copy up origin dentry is not available for
verification.

Relax the check in case copy up origin dentry is not available.

Fixes: b9ac5c274b8c ("ovl: hash overlay non-dir inodes by copy up...")
Reported-by: Jordi Pujol <jordipujolp@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/overlayfs/inode.c |   11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -576,10 +576,13 @@ static int ovl_inode_set(struct inode *i
 static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
 			     struct dentry *upperdentry)
 {
-	struct inode *lowerinode = lowerdentry ? d_inode(lowerdentry) : NULL;
-
-	/* Lower (origin) inode must match, even if NULL */
-	if (ovl_inode_lower(inode) != lowerinode)
+	/*
+	 * Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL.
+	 * This happens when finding a copied up overlay inode for a renamed
+	 * or hardlinked overlay dentry and lower dentry cannot be followed
+	 * by origin because lower fs does not support file handles.
+	 */
+	if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry))
 		return false;
 
 	/*


Patches currently in stable-queue which might be from amir73il@gmail.com are

queue-4.13/ovl-fix-false-positive-estale-on-lookup.patch