Subject: Re: WARNING in __rcu_read_unlock

From: Stefano Brivio <[email-masked]>
Date: Mon, 17 Dec 2018 16:24:21 +0100

On Mon, 17 Dec 2018 06:57:35 -0800
Eric Dumazet <[email-masked]> wrote:

> Might be cause by commit b8a51b38e4d4dec3e379d52c0fe1a66827f7cf1e
> fou, fou6: ICMP error handlers for FoU and GUE

This:

diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
index 0d0ad19ecb87..20a6de26d146 100644
--- a/net/ipv4/fou.c
+++ b/net/ipv4/fou.c
@@ -1008,6 +1008,9 @@ static int gue_err_proto_handler(int proto, struct sk_buff *skb, u32 info)
 {
        const struct net_protocol *ipprot = rcu_dereference(inet_protos[proto]);
 
+       if (ipprot == IPPROTO_UDP)
+               return -EINVAL;
+
        if (ipprot && ipprot->err_handler) {
                if (!ipprot->err_handler(skb, info))
                        return 0;

should fix the issue, but I still have to run tests and make sure we
don't hit similar cases.

-- 
Stefano