netdev - Re: ipqueue allocation failure.

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Message-ID: <1303277267.2756.14.camel@edumazet-laptop>
Date:	Wed, 20 Apr 2011 07:27:47 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	davej@...hat.com, netdev@...r.kernel.org
Subject: Re: ipqueue allocation failure.

Le mardi 19 avril 2011 à 20:41 -0700, David Miller a écrit :
> From: Dave Jones <davej@...hat.com>
> Date: Tue, 19 Apr 2011 21:42:22 -0400
> 
> > Not catastrophic, but ipqueue seems to be too trusting of what it gets
> > passed from userspace, and passes it on down to the page allocator,
> > where it will spew warnings if the page order is too high.
> > 
> > __ipq_rcv_skb has several checks for lengths too small, but doesn't
> > seem to have any for oversized ones.   I'm not sure what the maximum
> > we should check for is. I'll code up a diff if anyone has any ideas
> > on a sane maximum.
> 
> Maybe the thing to do is to simply pass __GFP_NOWARN to nlmsg_new()
> in netlink_ack()?
> 
> Anyone else have a better idea?
> --

It should be fine, since we already checked sk->sk_sndbuf in
netlink_sendmsg()

if (len > sk->sk_sndbuf - 32)
	goto out;

Maybe the 32 magic value is too small to take into account
struct nlmsgerr that is prepended in netlink_ack()

Hmm, no, sizeof(struct nlmsgerr) is 20



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