From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] phonet: Check input from user before allocating
Date: Mon, 02 Apr 2012 17:40:06 -0400 (EDT)
Message-ID: <20120402.174006.70116829696492189.davem@davemloft.net>
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	<201204022201.41808.remi@remlab.net>
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=46rom: "R=E9mi Denis-Courmont" <remi@remlab.net>
Date: Mon, 2 Apr 2012 22:01:40 +0300

> Le lundi 2 avril 2012 23:31:00 Sasha Levin, vous avez =E9crit :
>> A phonet packet is limited to USHRT_MAX bytes, this is never checked=
 during
>> tx which means that the user can specify any size he wishes, and the=
 kernel
>> will attempt to allocate that size.
>=20
> Does this really solve the problem?  I guess 128kb is still possible =
with=20
> USHRT_MAX plus skbuff overhead, which might still trigger OOM relativ=
ely=20
> easily once the memory gets sufficiently fragmented.
>=20
> How does UDP deal with this?

UDP generates a fragment list of MTU sized SKBs.

Phonet could avoid the large allocations by building page based
SKBs.