[PATCH 4.12 23/27] xfrm: policy: check policy direction value

Greg Kroah-Hartman
2017-09-05T07:13:07Z

From: Vladis Dronov <vdronov@redhat.com>

commit 7bab09631c2a303f87a7eb7e3d69e888673b9b7e upstream.

The 'dir' parameter in xfrm_migrate() is a user-controlled byte which is used
as an array index. This can lead to an out-of-bound access, kernel lockup and
DoS. Add a check for the 'dir' value.

This fixes CVE-2017-11600.

References: https://bugzilla.redhat.com/show_bug.cgi?id=1474928
Fixes: 80c9abaabf42 ("[XFRM]: Extension for dynamic update of endpoint address(es)")
Reported-by: "bo Zhang" <zhangbo5891001@gmail.com>
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/xfrm/xfrm_policy.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -3301,9 +3301,15 @@ int xfrm_migrate(const struct xfrm_selec
struct xfrm_state *x_new[XFRM_MAX_DEPTH];
struct xfrm_migrate *mp;

+ /* Stage 0 - sanity checks */
if ((err = xfrm_migrate_check(m, num_migrate)) < 0)
goto out;

+ if (dir >= XFRM_POLICY_MAX) {
+ err = -EINVAL;
+ goto out;
+ }
+
/* Stage 1 - find policy */
if ((pol = xfrm_migrate_policy_find(sel, dir, type, net)) == NULL) {
err = -ENOENT;