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From: Johannes Berg <johannes@sipsolutions.net>
To: Alexey Dobriyan <adobriyan@gmail.com>,
	David Miller <davem@davemloft.net>
Cc: netdev <netdev@vger.kernel.org>
Subject: Re: BROKEN Re: [PATCH] netlink: 2-clause nla_ok()
Date: Mon, 05 Dec 2016 16:09:13 +0100	[thread overview]
Message-ID: <1480950553.31788.40.camel@sipsolutions.net> (raw)
In-Reply-To: <CACVxJT9Qc=vNexx4ooQVFo=SrGs4-oHeZrnL18vbiS+o0F_N1A@mail.gmail.com> (sfid-20161205_155731_995936_F14B01DF)


> Maybe someone could vouch that other checks prevent
> this kind of situation from happening but not me.

No, now that you spell it out (and I see the patch) - this is
absolutely needed because nla_for_each_attr() [1] can be called on
arbitrary data coming from userspace in a message, e.g. by way
of nla_for_each_nested(). Even if it's not malformed, nla_ok() is the
only abort condition for that loop, so it would read at least one
nla_len after the real buffer without that condition.

johannes

[1] which seems to be the only significant user thereof

  reply	other threads:[~2016-12-05 15:09 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-05 14:56 BROKEN Re: [PATCH] netlink: 2-clause nla_ok() Alexey Dobriyan
2016-12-05 15:09 ` Johannes Berg [this message]
2016-12-13 19:30   ` [PATCH net-next] netlink: revert broken, broken "2-clause nla_ok()" Alexey Dobriyan
2016-12-13 19:55     ` David Miller

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