[3.16.y-ckt stable] Patch "dcache: fix kmemcheck warning in switch_names" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    dcache: fix kmemcheck warning in switch_names

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 70fe6081473c3d9be719a3cae2b0b6e55c949da5 Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka at redhat.com>
Date: Fri, 5 Sep 2014 12:16:01 -0400
Subject: dcache: fix kmemcheck warning in switch_names

commit 08d4f7722268755ee34ed1c9e8afee7dfff022bb upstream.

This patch fixes kmemcheck warning in switch_names. The function
switch_names swaps inline names of two dentries. It swaps full arrays
d_iname, no matter how many bytes are really used by the strings. Reading
data beyond string ends results in kmemcheck warning.

We fix the bug by marking both arrays as fully initialized.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Signed-off-by: Al Viro <viro at zeniv.linux.org.uk>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/dcache.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index 1d8b6a310822..e43ac3ca37e6 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2436,6 +2436,8 @@ static void switch_names(struct dentry *dentry, struct dentry *target,
 			 */
 			unsigned int i;
 			BUILD_BUG_ON(!IS_ALIGNED(DNAME_INLINE_LEN, sizeof(long)));
+			kmemcheck_mark_initialized(dentry->d_iname, DNAME_INLINE_LEN);
+			kmemcheck_mark_initialized(target->d_iname, DNAME_INLINE_LEN);
 			if (!exchange) {
 				memcpy(dentry->d_iname, target->d_name.name,
 						target->d_name.len + 1);
--
2.1.4