@@ -426,6 +426,9 @@ u32 ovs_vport_find_upcall_portid(const struct vport *vport, struct sk_buff *skb)
return ids->ids[ids_index];
}
+static DEFINE_PER_CPU(int, ovs_recursion);
+static const int ovs_recursion_limit = 8;
+
/**
* ovs_vport_receive - pass up received packet to the datapath for processing
*
@@ -442,6 +445,14 @@ int ovs_vport_receive(struct vport *vport, struct sk_buff *skb,
struct sw_flow_key key;
int error;
+ if (__this_cpu_inc_return(ovs_recursion) > ovs_recursion_limit) {
+ net_crit_ratelimited("ovs: recursion limit reached on datapath %s, probable configuration error\n",
+ ovs_dp_name(vport->dp));
+ error = -ENETDOWN;
+ kfree_skb(skb);
+ goto out;
+ }
+
OVS_CB(skb)->input_vport = vport;
OVS_CB(skb)->mru = 0;
if (unlikely(dev_net(skb->dev) != ovs_dp_get_net(vport->dp))) {
@@ -457,10 +468,13 @@ int ovs_vport_receive(struct vport *vport, struct sk_buff *skb,
error = ovs_flow_key_extract(tun_info, skb, &key);
if (unlikely(error)) {
kfree_skb(skb);
- return error;
+ goto out;
}
+
ovs_dp_process_packet(skb, &key);
- return 0;
+out:
+ __this_cpu_dec(ovs_recursion);
+ return error;
}
EXPORT_SYMBOL_GPL(ovs_vport_receive);
It was seen that defective configurations of openvswitch could overwrite the STACK_END_MAGIC and cause a hard crash of the kernel because of too many recursions within ovs. This problem arises due to the high stack usage of openvswitch. The rest of the kernel is fine with the current limit of 10 (RECURSION_LIMIT). Thus add an extra recursion limit counter for ovs_vport_receive until parts of the stack usage is moved to percpu scratch space. Cc: Pravin Shelar <pshelar@ovn.org> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> --- net/openvswitch/vport.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)