From: Daniel Borkmann <dborkman@redhat.com>
Date: Tue, 3 Sep 2013 17:29:12 +0000 (+0200)
Subject: net: ipv6: tcp: fix potential use after free in tcp_v6_do_rcv
X-Git-Tag: v3.12-rc1~132^2~1^2~7
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3a1c756590633c0e86df606e5c618c190926a0df;p=pandora-kernel.git

net: ipv6: tcp: fix potential use after free in tcp_v6_do_rcv

In tcp_v6_do_rcv() code, when processing pkt options, we soley work
on our skb clone opt_skb that we've created earlier before entering
tcp_rcv_established() on our way. However, only in condition ...

  if (np->rxopt.bits.rxtclass)
    np->rcv_tclass = ipv6_get_dsfield(ipv6_hdr(skb));

... we work on skb itself. As we extract every other information out
of opt_skb in ipv6_pktoptions path, this seems wrong, since skb can
already be released by tcp_rcv_established() earlier on. When we try
to access it in ipv6_hdr(), we will dereference freed skb.

[ Bug added by commit 4c507d2897bd9b ("net: implement IP_RECVTOS for
  IP_PKTOPTIONS") ]

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

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