[Lucid CVE 2/3] xfrm_user: fix info leak in copy_to_user_policy()

[Luis Henriques]

From: Mathias Krause <minipli at googlemail.com>

CVE-2012-6537

BugLink: http://bugs.launchpad.net/bugs/1156716

The memory reserved to dump the xfrm policy includes multiple padding
bytes added by the compiler for alignment (padding bytes in struct
xfrm_selector and struct xfrm_userpolicy_info). Add an explicit
memset(0) before filling the buffer to avoid the heap info leak.

Signed-off-by: Mathias Krause <minipli at googlemail.com>
Acked-by: Steffen Klassert <steffen.klassert at secunet.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit 7b789836f434c87168eab067cfbed1ec4783dffd)

Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/xfrm/xfrm_user.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index ab5f23c..0926b00 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1075,6 +1075,7 @@ static void copy_from_user_policy(struct xfrm_policy *xp, struct xfrm_userpolicy
 
 static void copy_to_user_policy(struct xfrm_policy *xp, struct xfrm_userpolicy_info *p, int dir)
 {
+	memset(p, 0, sizeof(*p));
 	memcpy(&p->sel, &xp->selector, sizeof(p->sel));
 	memcpy(&p->lft, &xp->lft, sizeof(p->lft));
 	memcpy(&p->curlft, &xp->curlft, sizeof(p->curlft));
-- 
1.8.1.2