From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net-next v2 02/16] l2tp: add RCU read lock to protect
 tunnel ptr in ip socket destroy
Date: Mon, 12 Feb 2018 11:22:09 -0500 (EST)
Message-ID: <20180212.112209.2187177765716436115.davem@davemloft.net>
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From: James Chapman <jchapman@katalix.com>
Date: Mon, 12 Feb 2018 10:11:06 +0000

> If an L2TPIP socket is closed, add RCU protection when we deref
> sk_user_data to prevent races with another thread closing the same
> tunnel.
> 
> Fixes: 0d76751fad ("l2tp: Add L2TPv3 IP encapsulation (no UDP) support")

Another patch with no signoff, and:

>  refcount_t: increment on 0; use-after-free.
>  WARNING: CPU: 2 PID: 2892 at lib/refcount.c:153 refcount_inc+0x2b/0x30
>  Modules linked in:
>  CPU: 2 PID: 2892 Comm: pppol2tp_chaos Not tainted 4.15.0-rc9+ #1
 ...

a kernel log dump which should be in the commit message body.