linux-kernel - [34/90] cifs: cope with negative dentries in cifs_get

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Date:	Fri, 12 Aug 2011 14:04:19 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Al Viro <viro@...IV.linux.org.uk>,
	Jeff Layton <jlayton@...hat.com>,
	Steve French <sfrench@...ibm.com>
Subject: [34/90] cifs: cope with negative dentries in cifs_get_root

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Jeff Layton <jlayton@...hat.com>

commit 80975d21aae2136ccae1ce914a1602dc1d8b0795 upstream.

The loop around lookup_one_len doesn't handle the case where it might
return a negative dentry, which can cause an oops on the next pass
through the loop. Check for that and break out of the loop with an
error of -ENOENT if there is one.

Fixes the panic reported here:

    https://bugzilla.redhat.com/show_bug.cgi?id=727927

Reported-by: TR Bentley <home@...rbentley.net>
Reported-by: Iain Arnell <iarnell@...il.com>
Cc: Al Viro <viro@...IV.linux.org.uk>
Signed-off-by: Jeff Layton <jlayton@...hat.com>
Signed-off-by: Steve French <sfrench@...ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 fs/cifs/cifsfs.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -581,6 +581,10 @@ cifs_get_root(struct smb_vol *vol, struc
 		mutex_unlock(&dir->i_mutex);
 		dput(dentry);
 		dentry = child;
+		if (!dentry->d_inode) {
+			dput(dentry);
+			dentry = ERR_PTR(-ENOENT);
+		}
 	} while (!IS_ERR(dentry));
 	_FreeXid(xid);
 	kfree(full_path);


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