From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net] netlink: extack needs to be reset each time
 through loop
Date: Mon, 15 Jan 2018 13:50:31 -0500 (EST)
Message-ID: <20180115.135031.2251496604167847341.davem@davemloft.net>
References: <20180110210039.4763-1-dsahern@gmail.com>
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Cc: netdev@vger.kernel.org, johannes.berg@intel.com
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From: David Ahern <dsahern@gmail.com>
Date: Wed, 10 Jan 2018 13:00:39 -0800

> syzbot triggered the WARN_ON in netlink_ack testing the bad_attr value.
> The problem is that netlink_rcv_skb loops over the skb repeatedly invoking
> the callback and without resetting the extack leaving potentially stale
> data. Initializing each time through avoids the WARN_ON.
> 
> Fixes: 2d4bc93368f5a ("netlink: extended ACK reporting")
> Reported-by: syzbot+315fa6766d0f7c359327@syzkaller.appspotmail.com
> Signed-off-by: David Ahern <dsahern@gmail.com>

Applied and queued up for -stable, thanks David.