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From: "David S. Miller" <davem@redhat.com>
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Date: Thu, 24 May 2001 16:17:55 -0700 (PDT)
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: engler@csl.Stanford.EDU (Dawson Engler), linux-kernel@vger.kernel.org,
        mc@cs.Stanford.EDU
Subject: Re: [CHECKER] free bugs in 2.4.4 and 2.4.4-ac8
In-Reply-To: <E1533qI-0005jT-00@the-village.bc.nu>
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	<E1533qI-0005jT-00@the-village.bc.nu>
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Alan Cox writes:
 > > [BUG]  seems possible --- or is some precondition guarenteed?
 > > /u2/engler/mc/oses/linux/2.4.4-ac8/net/ipv6/udp.c:438:udpv6_recvmsg: ERROR:FREE:453:438: WARN: Use-after-free of "skb"! set by 'kfree_skb':453
 > 
 > Looks right. Left for DaveM

It's wrong, in the MSG_PEEK case skb->users is incremented by
skb_recv_datagram, so to truly get rid of it we do indeed need to
unlink it from the receive_queue then free it twice :-)

Later,
David S. Miller
davem@redhat.com