[SRU][lts-utopic] ovl: use O_LARGEFILE in ovl_copy_up()

[Luis Henriques]

From: David Howells <dhowells at redhat.com>

Open the lower file with O_LARGEFILE in ovl_copy_up().

Pass O_LARGEFILE unconditionally in ovl_copy_up_data() as it's purely for
catching 32-bit userspace dealing with a file large enough that it'll be
mishandled if the application isn't aware that there might be an integer
overflow.  Inside the kernel, there shouldn't be any problems.

Reported-by: Ulrich Obergfell <uobergfe at redhat.com>
Signed-off-by: David Howells <dhowells at redhat.com>
Signed-off-by: Miklos Szeredi <miklos at szeredi.hu>
Cc: <stable at vger.kernel.org> # v3.18+
(cherry picked from commit 0480334fa60488d12ae101a02d7d9e1a3d03d7dd)
BugLink: https://bugs.launchpad.net/bugs/1523000
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/overlayfs/copy_up.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index ea1ec4933b14..092c6b79c14b 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -80,11 +80,11 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
 	if (len == 0)
 		return 0;
 
-	old_file = ovl_path_open(old, O_RDONLY);
+	old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
 	if (IS_ERR(old_file))
 		return PTR_ERR(old_file);
 
-	new_file = ovl_path_open(new, O_WRONLY);
+	new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
 	if (IS_ERR(new_file)) {
 		error = PTR_ERR(new_file);
 		goto out_fput;