xps: must clear sender_cpu before forwarding
John reported that my previous commit added a regression
on his router.
This is because sender_cpu & napi_id share a common location,
so get_xps_queue() can see garbage and perform an out of bound access.
We need to make sure sender_cpu is cleared before doing the transmit,
otherwise any NIC busy poll enabled (skb_mark_napi_id()) can trigger
this bug.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: John <jw@nuclearfallout.net>
Bisected-by: John <jw@nuclearfallout.net>
Fixes: 2bd82484bb4c ("xps: fix xps for stacked devices")
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index 787b3c2..d9bc28a 100644
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -67,6 +67,7 @@
if (unlikely(opt->optlen))
ip_forward_options(skb);
+ skb_sender_cpu_clear(skb);
return dst_output(skb);
}