xfrm: do not assume that template resolving always returns xfrms

xfrm_resolve_and_create_bundle() assumed that, if policies indicated presence of xfrms, bundle template resolution would always return some xfrms. This is not true for 'use' level policies which can result in no xfrm's being applied if there is no suitable xfrm states. This fixes a crash by this incorrect assumption. Reported-by: George Spelvin <[email protected]> Bisected-by: George Spelvin <[email protected]> Tested-by: George Spelvin <[email protected]> Signed-off-by: Timo Teräs <[email protected]> Signed-off-by: David S. Miller <[email protected]>
naresharelli · Jul 14, 2010 · d809ec8 · d809ec8
1 parent ab83a38
commit d809ec8
Showing 1 changed file with 13 additions and 2 deletions.
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
@@ -1594,8 +1594,8 @@ xfrm_resolve_and_create_bundle(struct xfrm_policy **pols, int num_pols,
 
 	/* Try to instantiate a bundle */
 	err = xfrm_tmpl_resolve(pols, num_pols, fl, xfrm, family);
-	if (err < 0) {
-		if (err != -EAGAIN)
+	if (err <= 0) {
+		if (err != 0 && err != -EAGAIN)
 			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTPOLERROR);
 		return ERR_PTR(err);
 	}
@@ -1678,6 +1678,13 @@ xfrm_bundle_lookup(struct net *net, struct flowi *fl, u16 family, u8 dir,
 			goto make_dummy_bundle;
 		dst_hold(&xdst->u.dst);
 		return oldflo;
+	} else if (new_xdst == NULL) {
+		num_xfrms = 0;
+		if (oldflo == NULL)
+			goto make_dummy_bundle;
+		xdst->num_xfrms = 0;
+		dst_hold(&xdst->u.dst);
+		return oldflo;
 	}
 
 	/* Kill the previous bundle */
@@ -1760,6 +1767,10 @@ int __xfrm_lookup(struct net *net, struct dst_entry **dst_p, struct flowi *fl,
 				xfrm_pols_put(pols, num_pols);
 				err = PTR_ERR(xdst);
 				goto dropdst;
+			} else if (xdst == NULL) {
+				num_xfrms = 0;
+				drop_pols = num_pols;
+				goto no_transform;
 			}
 
 			spin_lock_bh(&xfrm_policy_sk_bundle_lock);