ipv6: probe routes asynchronous in rt6_probe

Routes need to be probed asynchronous otherwise the call stack gets
exhausted when the kernel attemps to deliver another skb inline, like
e.g. xt_TEE does, and we probe at the same time.

We update neigh->updated still at once, otherwise we would send to
many probes.

Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 31 insertions, 7 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index c1ee3813e1ae..f54e3a101098 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -476,6 +476,24 @@ out:
 }
 
 #ifdef CONFIG_IPV6_ROUTER_PREF
+struct __rt6_probe_work {
+        struct work_struct work;
+        struct in6_addr target;
+        struct net_device *dev;
+};
+
+static void rt6_probe_deferred(struct work_struct *w)
+{
+        struct in6_addr mcaddr;
+        struct __rt6_probe_work *work =
+                container_of(w, struct __rt6_probe_work, work);
+
+        addrconf_addr_solict_mult(&work->target, &mcaddr);
+        ndisc_send_ns(work->dev, NULL, &work->target, &mcaddr, NULL);
+        dev_put(work->dev);
+        kfree(w);
+}
+
 static void rt6_probe(struct rt6_info *rt)
 {
         struct neighbour *neigh;
@@ -499,17 +517,23 @@ static void rt6_probe(struct rt6_info *rt)
 
         if (!neigh ||
             time_after(jiffies, neigh->updated + rt->rt6i_idev->cnf.rtr_probe_interval)) {
-                struct in6_addr mcaddr;
-                struct in6_addr *target;
+                struct __rt6_probe_work *work;
+
+                work = kmalloc(sizeof(*work), GFP_ATOMIC);
 
-                if (neigh) {
+                if (neigh && work)
                         neigh->updated = jiffies;
+
+                if (neigh)
                         write_unlock(&neigh->lock);
-                }
 
-                target = (struct in6_addr *)&rt->rt6i_gateway;
-                addrconf_addr_solict_mult(target, &mcaddr);
-                ndisc_send_ns(rt->dst.dev, NULL, target, &mcaddr, NULL);
+                if (work) {
+                        INIT_WORK(&work->work, rt6_probe_deferred);
+                        work->target = rt->rt6i_gateway;
+                        dev_hold(rt->dst.dev);
+                        work->dev = rt->dst.dev;
+                        schedule_work(&work->work);
+                }
         } else {
 out:
                 write_unlock(&neigh->lock);