From mboxrd@z Thu Jan  1 00:00:00 1970
From: Johannes Berg <johannes@sipsolutions.net>
Subject: Re: [PATCH v4] af_netlink: ensure that NLMSG_DONE never fails in
 dumps
Date: Sat, 11 Nov 2017 15:18:00 +0100
Message-ID: <1510409880.12037.5.camel@sipsolutions.net>
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To: David Miller <davem@davemloft.net>, Jason@zx2c4.com
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> > If you're handling this by forcing another read() to procude the
> > NLMSG_DONE, then you have no reason to WARN_ON() here.
> > 
> > In fact you are adding a WARN_ON() which is trivially triggerable by
> > any user.
> 
> I added this in my suggestion for how this could work, but I don't
> think you're right, since we previously check if there's enough space.

Or perhaps I should say this differently:

Forcing another read happens through the

	skb_tailroom(skb) < nlmsg_total_size(...)

check, so the nlmsg_put_answer() can't really fail.


Handling nlmsg_put_answer() failures by forcing another read would have
required jumping to the existing if code with a goto, or restructuring
the whole thing completely somehow, and I didn't see how to do that.

johannes