xfrm: Fix a race in the xdst pcpu cache.

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@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: David Miller <davem@davemloft.net>,
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 6bc16bb..688ed34 100644 (file)
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2056,8 +2056,11 @@ xfrm_bundle_lookup(struct net *net, const struct flowi *fl, u16 family, u8 dir,
        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 *net, struct dst_entry *dst_orig,
                                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);