[PATCH 4.14 06/71] xfrm: Fix a race in the xdst pcpu cache.

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>

commit 76a4201191814a0061cb5c861fafb9ecaa764846 upstream.

We need to run xfrm_resolve_and_create_bundle() with
bottom halves off. Otherwise we may reuse an already
released dst_enty when the xfrm lookup functions are
called from process context.

Fixes: c30d78c14a813db39a647b6a348b428 ("xfrm: add xdst pcpu cache")
Reported-by: Darius Ski <darius.ski@xxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Acked-by: David Miller <davem@xxxxxxxxxxxxx>,
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/xfrm/xfrm_policy.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2056,8 +2056,11 @@ xfrm_bundle_lookup(struct net *net, cons
 	if (num_xfrms <= 0)
 		goto make_dummy_bundle;
 
+	local_bh_disable();
 	xdst = xfrm_resolve_and_create_bundle(pols, num_pols, fl, family,
-						  xflo->dst_orig);
+					      xflo->dst_orig);
+	local_bh_enable();
+
 	if (IS_ERR(xdst)) {
 		err = PTR_ERR(xdst);
 		if (err != -EAGAIN)
@@ -2144,9 +2147,12 @@ struct dst_entry *xfrm_lookup(struct net
 				goto no_transform;
 			}
 
+			local_bh_disable();
 			xdst = xfrm_resolve_and_create_bundle(
 					pols, num_pols, fl,
 					family, dst_orig);
+			local_bh_enable();
+
 			if (IS_ERR(xdst)) {
 				xfrm_pols_put(pols, num_pols);
 				err = PTR_ERR(xdst);